What is Hermetic Architecture *for*?

This isn't correct. You can very easily construct a small item that includes a T: Room effect. In fact, you can enchant a brick and use it to build the wall, if you want an integrated effect.

Frankly in this direction it's just best to just require one enchanting project instead of many, just fiat allowing "If you can make the Geometry roll, you may enchant structures of any size without bringing them into your laboratory". Without adding more guidelines relating to RoP:M/F rules you still run into ye olde why problem, but it's less utterly insane to bother. Speaking of:

Guess you got me: A totally crazy Archmage the likes the Order has never seen can assemble a group of harmoniously spec'd other Mages the likes the Order has never seen to subserviate themselves to a project the likes of... that same archmage building a magical monument (like a standing stone) and waiting that 100 years it took for him to gain such specialized power, at which point if used his magical monument gains +1 tether score all on its own. This is good rules text.

Technically thompsja is correct. Vanilla AM5 does not allow a room to be enchanted, meaning made into an enchanted item that contains one or more magical effects.

However, vanilla Hermetic Magic (either spells or enchantment effects) can easily affect a room target at any given range. This usually produces the desired result. All that is required is to add a Range modifier to the spell description.

For example, consider the spell Vision of the Haunting Spirits (AM5 pg. 150). A Magus can easily enchant a floor tile with the effect at it's normal Range and Target (Touch and Room) to effect the entire room. Alternately, if the Magus is enchanting his own lab, he can enchant the room itself and drop the Range to Personal, saving a whopping 1 Magnitude on the enchantment. This is not much of an argument for using Hermetic Architecture.

TMRE was an early book in the AM5 line and I suspect that the above was not well understood at the time. I also suspect that the ability to affect targets of arbitrary large sizes by simply adding magnitudes to the effect (AM5 pg. 113) was not well understood, since the HA material seems to imply that large structures require Boundary targets.

Your suggested removal of multiplying work in addition to adding guidelines to interact with RoP:M/F aura rules would give the virtue a sort of purpose, that seems like a good direction for houseruling.

I've still been absurdly busy with holiday aftermath etc, but the workflow I've devised so far is a mix of the Sacred Architecture [SA] workflow and existing HA workflow. The HA workflow is:

1) Devise Enchantment    [Int+Geometry+Bonuses] vs [6 + Target Size] threshold check   0 Seasons
2) Open Devices         (Labwork) Spend [Material X Size[sup]2[/sup]] pawns           [Size] Seasons Minimum
3) Enchant Devices      (Labwork) Spend normal vis for enchanting                     [Size] Seasons Minimum
4) Finish Enchantment   [MuVi casting score] vs [highest enchantment +5-15]           0 Seasons

The SA workflow is divided for the three types of project, but are basically of this form with slightly different modifiers Aura Aspects (Adding virtues to auras)
1) Design Project         [Int+SA+MT+Mu+Vi+Bonuses] vs [Based on Project]             1 Season
2) Build Project          [Per+Craft+Aura+Stress] vs [Project level]*                 Variable Seasons
3) Implement Project      Success Threshold in 2 per season to level aspect           Variable Seasons
4) Upkeep project^         Aspect decays if you don't spend time on it                 Variable Seasons
                                                                                      (1 season can last years)
*This is checked at the end of the crafting and is kept for further use
^Only Aspecting an aura requires upkeep

So, there are a few big differences between SA and HA, some of which are a result of the overall different expectations. Notably, SA requires no vis but requires a lot more mundane effort to construct and upkeep the sacred building. there are similarities: First there is a design step ability gate, you check if you can even design the effect and stop if you cannot. Next there is are labwork-type steps, where you check your score against a target, note down how much your score beats the threshold and continue until your points equal the level of the effect. Last there's some kind of implementation or upkeep step that requires expending resources, vis in Bind the Mystic Structure and mundane effort in SA.

Text I have so far for Revised Hermetic Architecture [RHA]. It's still quite rough and needs refining, and I need to put hard thought to the guidelines.

Revised Hermetic Architecture governs three major techniques utilizing grand construction projects known as Edifices:
The art of creating Aura tethers
The art of modfying Auras
The art of enchanting Auras

This virtue requires Hermetic Geometry, and edifices must be constructed in a way that qualifes for the bonuses of Hermetic Geometry - but the benefits of those bonuses apply to Lab and Ritual totals. Arithmetic Book Bonuses apply to Lab Totals and mystery rituals if the book can be consulted. Calculations within this mystery use Artes Liberales (Geometry).

Made up of component parts arranged in auspicious ways within an aura. Often these take the form of an auspicious structure, but can also be several discrete small installations in auspicious places, such as a ring of stones arranged in astrologically significant locations around a sacred grove.

My workflow for Revised Hermetic Architecture [RHA], for the moment at least, is below.

1) Devise Edifice	     [Int+Geo+MT+Bonuses] vs [6 + Target Size + Aura Strength]  0 Seasons
2) Construct Components   Standard Labwork for effects*, vis cost                    Variable Seasons
3) Bind Edifice		     Bind the Mystic Structure, vis cost. Do NOT need to learn. 0 Seasons
4) Integrate Edifice	   (? Certainly on Tethering)                                 Variable Seasons

*This works differently than regular enchanting

Devise Step:
[Int + Artes Liberales (Geometry) + MT + bonuses] vs [6 + Target Size + Aura Strength] to devise edifice. Target can be a structure or an entire aura: You do not need to target the entire aura, but you may. Standard full Aura is size 8. Numerology Book bonuses apply, +1 for consulting an craftsman with a 5+ in the primary form of the edifice. Will need [Size] components. The form is typically a building with auspicious icons and architecture (cathedral/temple) or a series of monuments arranged in a magical way (ring of standing stones).

Construct Step:
This is a mystery activity and therefore only those party to the mystery understand lab texts produced. All of the component devices are enchanted at once during this mystery activity! Also notably: Bonuses to opening devices or spending vis on enchantments do not apply but bonuses to lab totals for enchanting items do apply.
Calculate effect level via guideline table (TBA). +1 level for every required device to complete edifice.
[Int + MT + Geometry + Creo/Muto/Rego + Vim + lab bonuses] for lab total, accrue points over the effect to complete (as regular invention/enchantment). Must spend pawns total over the process as if to open target boundary (SizeXMaterial). May experiment, with the usual benefits and risks. In other words, even if you have double the effect level in lab total (completing the mystery enchantment over one season), if you cannot handle that much vis in one season you must take more time to perform the mystery enchantment.

Bind Edifice
Arrange the Edifice components as set out during the Devise Step, placing them auspiciously into a magical structure. This CAN just be comprised of the Edifice components, but usually includes a mundane construction project to house the components. For outdoor components, a version of Hiding the Mystic Key is used to protect the components from the elements.
Cast a Binding the Mystic Structure ritual as described in HA. You need spend time learning this ritual, devising the precise ritual required is part of the Devise calculation and the secrets of this Mystery. You simply must be able to cast a properly powerful ritual and have the vis to do so.

Integrate Edifice
I'm still toying with this idea, basically a version of SA's slow onset effects. It makes sense for me that the effects of this virtue should take a little while to come into effect, as the Edifice's influence propagates out into the aura. At any rate, it should not take meaningful additional resources beyond protecting the edifice from undue harm or disruption. That way, you can't use this virtue to whipcrack effects back and forth to optimize it (I.E. Aspect it to Muto for research on a muto effect, aspect it to Rego the next season for a new lab project and so on). I think I'm just going to have it be a flat effect that charges up a magnitude per season or so on. Might limit it to some of the effects in specific. Will circle back around to this once the guidelines are roughed.

So.. Changelog:
Step 1: Adds MT and Geo bonuses, but adds aura strength to the ease factor.
Step 2: Enchanting the components is a mystery activity and is dramatically cheaper and easier because you do it all at once. On the other hand, it's harder to hyper optimize this step. However, there aren't rules for regular enchantments in this virtue - you can only use it for the special aura guidelines. Not sure how I feel about that, perhaps another minor virtue allows it, or I can jigger this slightly to allow enchanting an aura (as in, causing an aura to become an enchanted object).
Step 3: It's explicit that you need not learn Bind the Mystic Structure. Just another scores gate, but this one you can Wizards Communion or spend extra vis or whatever to cast it (and get ceremonial bonuses and so on).

What I'm going to do tonight is work backwards from some example mages of varying power (Average, Strong, Archmagus) and what they can reasonably cast, and devise guidelines based on those assumptions.

Haven't forgotten about this, just gotten very busy with the beginning of a new term etc. etc. Hopefully this weekend I'll be able to tackle finishing my thought here.

Okay, at these numbers I ran some calculations to see if things need tweaking and to determine base values for the enchantment guidelines. I ballparked a reasonable "Novice Architect" score, including scores reasonable for an unspecialized magus a few years past gauntlet who could have access to RHA. I also generated potential scores for a "Master Architect", who has a reasonably specialized laboratory and dramatically higher scores, as well as more bonuses (such as a maxed out numerologist's book and an apprentice).

According to my estimates, the Novice will have a score of ~17 in the Devise step, which means that he could affect a standard size 8 aura of up to strength 3. A Master level Architect would have a score of at least twice that, which means an aura score of 20 at size 8. I believe I'm going to add a factor including the number/depth of regios in the target area, to give the overflow score some value (and further limit weaker Architects).

In the Invest Step, the Novice and Master diverge, as they now add their arts scores. Novice has ~35, the Master has a lab total of 90. With those numbers and the existing guidelines in the Mysteries and RoP:M I generated this first draft of the mystery spell guidelines:

Creo Vim: Create/Strengthen Aura Tether by 1 (Total 30+5 per maximum pret. tether in aura) Muto Vim: Double of Halve size of aura/Regio (Base 4) (Min. 20 for boundary) Rego Vim: Gate between regio levels (Base 15) (Min. 35) Muto Vim: Tint Aura (Base 5*Level) (Min 25 for boundary) Muto Vim: Aspect Aura (Base: Aura*10+5) (Min 25 for boundary)

With an invent score of 35, the novice cannot create Aura Tethers, but he can tint and aspect auras, particularly if he is not trying to affect the full aura. There are several useful effects he can accomplish, from giving instilling personality traits in covenfolk to boosting particular types of labwork via aspecting, or toying with regio boundaries. There's enough there that I think the guidelines are a success in that respect - you don't need to be a crazy nutter superpowerful magus to use the virtue.

The other stumbling point with HA was the hypothetical "Super powerful magus attempting to boost an aura". It was just so... piddly compared to the extreme effort and cost required. With these guidelines, the highest level effect is creating a strength 5 preternatural tether, which has a total of 55, easily within reach. This means that the Master can pretty easily boost an aura by +5 by serially boosting an edifice's tether score +1 at a time, but only if the aura isn't capped out on preternatural tethers already. I think that limit really caps how powerful this can be, without needing to get into the crazytown high base levels required in HA.

The real project of a mad Master magus in RHA isn't empowering auras (which ultimately isn't that strong), but in aspecting them, or parts of them. Raising an aura by 1 gives +1 bonus. Aspecting an aura gives you the full strength of the aura as a bonus, but to more limited activity. The costs for that can easily get up to high levels/costs, and are of more limited general utility.

All that needs work at this point is revisiting and revising the exact numbers, and smoothing out the rules. Aspecting and Tethering will need some cooldown/windup rules, for the setting if nothing else. Rapidly boosting or twisting an aura will shatter it, creating Regiones or worse, as described in RoP:M. Outside of the bounds of the mystery, for sure. I think it's easier than I thought it would be to allow regular, non-mystery enchanting guidelines using the same rules, too.

To reapproach the original question, I wonder if Hermetic Architecture could be better described as building magical structures. Not physical structures, magical ones - enchantments of places as defined by boundaries, founding magical auras, constructing regios. All of these can be expressed as buildings, but the structure is the abstract and mystical, rather than the solid, physical, building.

Or is that simply obvious and I've missed the underlying assumption?

I throw my voice in as agreeing the difficulties are overly high. I suspect a rebuild of the guidelines is in order.

What do you think of my last two posts?

I've proposed a revised virtue that A) Fixes the huge vis and effort costs, and B) has more sensible guidelines. Swapping the aura boosting guidelines to interact with the tethering system means that it's not harder in higher natural auras, but is limited to boosting the aura as high as adding preternatural tethers can. There are still some really expensive projects you can devise with the revised virtue, but the main unique thing the virtue does isn't insanely and prohibitively difficult anymore, merely difficult.

I guess the next question is "Does this do what it should do to be cool/interesting/Mythic?"

Right now, though I think you have solved HA's biggest mathematical flaws, will the rules encourage Magi to create giant crazy towers (or what have you) to contest the rise of Cathedrals that are starting to go up all over Europe starting in the last 12th and through the 13th century? The HA Mystery was written to be a hermetic response to the mundane trend to create vast structures, and to give the Hermetics something similar.

How can recapture the color of the HA Virtue while maintaining the mathematical corrections of your RHA?

RHA allows for the bolstering and Aspecting auras. Remember that the strange rules and features of regios and Magical areas are a virtue of the aspects of their auras. The mage's answer to a cathedral is a wizards tower that amplifies and extends an aura across a town, spreading a feeling of awe and loyalty to all mundanes nearby, and slowly warping the area to the demands of the magi.

That functionally is the effect of cathedrals, I think?

Silly thought.
Does the spell "Hermes Portal" ReTe75 and the enchanted device Mercere Portal can be both considered to bend space.
How would that influence Hermetic Architecture?

I don't understand your question.

Hermes portal and the enchanted version are teleporting spells, not space bending spells. They don't fold space to make distant points close, they move the target from one location to another: they work on the target, not the location.

None of that has to do with Hermetic Architecture though...

I must admit that "bending space" is my shorthand for "Creates a magical portal throuh which, people, animals and objects can travel almost instantaneously. The ritual must be cast twice, simultaneously, at two different locations, and after the rituals are performed there is a magical connection between them."
From Hermes Portal ReTe75 ritual on p156 of ArM5.

I keep thinking that this extra "entrance" would change the topology of the room, and hence possible affect Hermetic Architecture.
And the feng shui. if you let that in your saga.

Seeing as topology as a concept doesn't really exist until some point between Euler's 18th century work and 20th century mathematicians, and the philosophy of space is vague until Newton and Liebnitz, your magus will probably not think of Hermes portals in modern ways. Being used to regiones and the concept of the Magic realm and Arcadia, your magus probably figures there are multiple overlapping realities and what you perceive depends on your senses.

Now a method of creating region entrances and connecting distant regiones would be useful for Hermetic Architecture - it would give a reason for regio networks (like the access to regio network virtue in RoP:M) and make people try to examine any strange standing stones they found inside a regio on the off-chance they detect the sigil of a well-known Hermetic architect. Maybe the cult of Mercury would have left such things?

Both Hermetic Architecture and my Revised version already include guidelines for creating regio entrances. Didja read the thread?

Wait....I got the impression you could create entrances from a mundane area into a regio, and then between different levels of the same regio. Are you saying that Hermetic Architecture has always been able to link, say, level 2 of a regio in Stonehenge with level 4 of a regio in Hibernia?

I absolutely have alwyas read it just like darkwing.

HA connects various levels of the same regio (including 'mundane'). Not different regiones.
For that, use Arcadian Travel (HoH: MC, p. 92).