Well, "bigger is better" could be a manifestation of Verditius Hubris. 
You're still not aiming high enough. Enchant a giant robot^H^H^H^H^Hautomaton and use it to fight rampaging monsters!
Enchanted towers are for wimps. You aren't a wimp, are you?
That's the rub. I'd stick a crystal ball or some such (perhaps a heroically proportioned bronze statue of the creator?) at an archetectually and dramatically appropriate location within the tower and open the tower as a compound item. This would allow you to enchant the entire tower as your talisman without even bending any of the published rules.
Being the main storyguide in the campaign d31m0z is talking about, I fully allow his unbridled lunacy. Alas, the other Magi of the covenant aren't nearly as megalomanic, so I guess he'll be miles past them in power soon enough.
Anyway, I still don't get the thing with Talismans. You have to open them up in one season right, or open them up as a compound item in several seasons. Then, when the item is assembled, you can attune it as a Talisman? Right? Have I finally figured it out? 
Eirik (aka Lutranaxx Magi ex Bjornaer)
A character has to open the item for enchantment just like any other item. Only after the item is opened can you make it a characrater's talisman.
Compound items need to be opened in a single season.
Talismans can be "opened further"
Talismans are fiddly, you've got to hit the rule book and re-read the invested device and talisman section carefully otherwise you'll surely have some ideas about talismans that don't match the ones that are lurking around in the minds of the people who did re-read the section carefully and that can lead to problems in play.
But can I make a staff with a gem on the top, and only enchent the gem? Would that then get the bonuses for being a staff? And could I open the staff for enchantment later, making it, in effect, two magic items?
E.
https://forum.atlas-games.com/t/talisman-components/107/1
This thread has an argument about the talisman rules full of quotes and examples. Also, at the end of the thread David pops in to say which position was the intent of the rules.
Actually I rather enjoy this idea. Hear me out since were in the land of the absurd. Most large structures are built by building a series of scaffolds and structural supports. These items allow brick, mortor, whatever to elevated to wherever and allow the structure to be built.
Build a scaffold/structural frame AROUND the place where the tower will be. This structure, on the OUTSIDE of the tower, will be the magi's LAB. Wet? Occasionally? Drafty? Certainly? Privacy? None at all.
However consider that this lab need only be temporary. Certainly there'll be 'some' penalities to the lab as it's entirely in exposed to the environment. However once the tower is enchanted, tear it down and build a proper lab inside your talisman.
Also, what comes after absurd?
That should probably contribute to the lab's Warping score. And conversely, lab accidents may have further unforeseen consequences. I could easily see the tower collapse into a sealed regio.
I would think the progression would go: 1) Conjure tower, 2) Instill lab in tower, 3) Enchant tower from within lab. In my saga there wouldn't be a problem doing it like that.
Of course, in my saga we had a clause added into the charter that any new buildings or stuctures built or conjured on the grounds had to have council approval. We foresaw the day coming when it would occur to the Creo mage, "I could make myself a tower" which might then draw undue attention for the locals.
(Although a really cool effect would be a MuMe effect at the new Verditious "Spectacle" range causing everyone who looked at it to think it had always been there.)
This is a nice amendment. While no one in my campaign has tried something of this magnitude, years ago our resident Bonisagus created a Creo Terram spell that basically creates a large stone 'igloo'. The motive was he was tired of sleeping in tents while on adventures. He didn't see why his accomodations on the road should be any worse than his accomodations at home.
Later, when creating his 'Staff of Power', he enchanted this effect into the item so he could build 'huts' for himself and his 'staff' while on adventures. The landscape was littered with stone huts where ever this mage went.
The amendment you proposed would have helped clean up our covenant.
OK, wrapping up what points I have managed to gleam from this little brainstorm:
1 - The Spell creates a volume of 70.000 cubic feet. And if a "small room" aproximately [12 x 12 x 8] 1.152 cubic feet, and has a Size value of x5, we can then say that the Tower would have a Size of x7 (Size multiplies by ten for every increment according to the Targets and Sizes table on pg. 113 of the AG0205).
2 - The Material of the Tower could be either Soft Stone (a value of x3) or Hard Stone (x4). But seeing as I want it to be white marble (it looks nice, okay?) that would certainly be Hard Stone. The Size and Material value would then be [4 x 7] 28 (alternatively [3 x 7] 21)
3 - This would require a Magic Theory score of 14 (alternatively 12) unless there are some additional rules in the Mystery Cults book that I have missed. It seemd to me that Urien indicated something of the sort. Clarification would be good.
4 - IF the Tower then became enchanted, it could then be instilled with an amount of vis equal to my highest Form and Technique.
5 - the question of wether the Tower needs be in a lab to be enchanted or if the lab can be in the Tower is not enirely without merit, but if one can enchant a large ship, then one should be able to enchant a Tower in like manner. The question can probably be discussed ad nauseum, but I cannay find the attraction.
Some questions pop up:
1 - What, if any, would the Shape and Material bonuses be for a marble Tower?
2 - Would living in ones own Talisman incease Warping? Other residents?
3 - Could, as Urien suggests, other Materials and possibly even Shapes be used to give the Tower other bonuses? Say doorframes lined with Lead or Iron for Warding?
Well, my Herbam mage was created with the idea that he'd eventually be able to conjure a house when he went traveling, and another character was inspired in part by the mystic tower thing.
Sadly, my house has gotten more and more complex, and requires increasingly higher levels to produce. (Although thanks to Covenants I can now set up a portable laboratory with it... the real challenge is the movable larder.)
To get more specific, yeah my brother who played this Bonisagus had spell levels to 'waste' so his huts, which were all the same were complex elaborately detailed constructs.
Because he wanted to make the spell strickly creo terram, everything in the 'hut' was made of stone. But he had a fireplace stocked with coal and brass shovel and brush to tend the fire. The windows were stained glass, there was a dinner table, made of stone and prepared with silver ware and plates. When the spell was cast, everything was considered one item. So the silverware had to be broken off the table, like it had a tab. There was seat for every original magus and the at the front door a mosaic displaying the founding of our covenant.
Here's the best part. He botched the spell while experimenting, so this entire structure, elaborate in it's beauty, was covered in dead insects, moths, flies, maggots ect. Long story why, but he had to build ANOTHER spell to clean his portable mansion everytime he build one. It was always a source of laughs as a garbage bad full of dead insects were pushed out the front door of every hut he built.
I love this stuff. I had a player that, in one lean year, decided to make a ritual to conjure food for the winter. He completely forgot about his Blatant Sigil flaw which caused maggots and the like to cover anything he casts a spell on. So, he basically wasted the season and the vis after the first casting. Normally I'd point things like this out before they happen, but I was sort of feeling like, "If you can't pay atention to your own flaws..."
hehe...I like that one Roger.
IIRC, marble is SOFT stone. One of the nice properties of marble is that it is easily carved, and polished. Granite is hard...very hard.
Elder Runes: Magic Theory times Philosophiae. Sooooo if your MT was 12, and your Philoshophiae was 6, your total would be 72....
You would be able to invest 72 pawns of Vim...(But you would be stuck with the additional 10 levels for each spell...assuming you put two runes on...)
Unless you have 30+ for both scores, you won't touch the example in #3.
Any place a Verditius decides is his lab.... 
I would say you can do it...the COOL factor alone makes it worth the while...
Questions:
Materials: whatever you put in it...Iron to hurt Faeries, brass for Ignem, spells, wood for ...well you get the point..
Shape: you have doors-transportation
Windows: Scrying
stairs...hmmm
a form of shelter...bonus to protection spells..maybe a +5
Warping: Absolutely NOT
Remember: if you include other materials, you have additional requisites for the original spell....
Love the idea, this is definitely cool 
Great Idea!!!
I imagine the entire party on a trip... And then, while the other maguses go camping, you just bring up your tower 
Oooooo. I like this! My comments are interspersed and below:
I would recommend also looking at the extended Material and Size Table on p97 of The Mysteries in teh Hermetic Architecture section. It seems, first of all to be more related to usable floorspace than volume, but your guess seems to track pretty well.
Not that anyone knew this at the time of M.E., but marble is metamorphosed limestone. Poor some white vinagar on a polished, but not sealed, marble tile sometime and let it sit for a while. Just don't do it on your wife's/girlfriend's pastry stone ... talk about Perdo Corpus at voice range! Oh, and Rego Corpus ward -- new Range = precisely equal to the distance from your bed to your couch. Sheesh!
Another option, if you are looking for stronger material that is less prone to laboratory stains would be to get a block of granite and do a Muto Terram ritual on it to turn it purest white. Plus, the quartz in granite would make it all sparkly...
Yep, ask your SG to lend you the Mystery Cults book and look up Elder Runes. There is a penalty adding 5 or 10 to any effect level but lets you enchant MT multiplied by Phil pawns on an item (p128, top of the third column). Pretty impressive!
Again, look up Elder Runes. With the right choice of runes, you get to double the highest Form AND Technique and if you choose a Rune related to a major or minor magical focus ... whew!
There are ways around this. The first is the scaffolding/temporary lab idea. There are some penalties but a little planning and sacrifice of perhaps 3 or 4 seasons of effort, they can be eliminated or reduced. Your SG will need to read and understand and communicate to you those penalties and effects from the Lab Specialization rules in Covenants.
The second method for circumventing the "must be inside the lab" requirement is to look into Hermetic Architecture in The Mysteries.
Also, Erik's point about the statue is SERIOUSLY worth looking into.
Off the top of my head, I would guess that "stoneworking", "sculpting", or "decorating buildings" would be apropriate. Hmm. Persue the Vulgar Alchemy secrets and find out! 
I would argue "no" for either you or your staff under "normal" circumsatnces. The taliman is a mystical extension of yourself so you and those you allow would be OK.
However, the idea of performing mystical experimentation, studying of vis, and other risky magical endeavors inside your mystical "self" bears thinking on. I'm sure your SG is suitably diabolical, but imagine what could happen if you botch a Perdo or Muto Corpus (or Mentem) effect. Warping will be only ONE of your problems!
Yes indeed. Consider adding a few sculptures in the studio or elsewhere of the shape bonuses that you want to invoke. Or put pristine examples of materials on display (and mystically connected to the tower).
With Vulgar Alchemy, Great Talisman, and Consummate Talisman mysteries under your belt, the grandness of this would be awe inspiring on the highest level. You would be INVITED to be an Archmagus!
Some more thoughts:
-- Carefully review the laboratory specialization rules in Covenants. With as much space as you are talking about, you can achive some pretty substantial lab bonuses. There are limits, but a Verditius would take what bonuses he could get.
-- In a similar vein, there are lab characteristic scores that have to be taken into account. Warping, in this context, is something I would review in detail. Also, Size, Refinement, and Health (remember that your lab is now attached to your person) have to be considered.
Invite your troupe to participate in some fashion. Persuit of this goal will generate a lot of stories and could easily dominate a saga. Just a thought.
Sir, I salute you. This is a truly grand idea. May you acheive your +9 "Great hermetic Architect" Reputation in short order!
Best,
-K!
Wow. 9 months to the day. Nice threadomancy.
It is my understanding that you do not need to inscribe the Elder Runes into the item you are working on. The knowledge that enables you to use the runes also allows you to use the increased vis total.
e.g. I am opening a small brass statue. It is a base metal (5) and it is larger than my hand so it is (4). It will take 20 pawns of vim to open it.
My stats are: MT 6, Phil 4
I cannot open it normally as my vis limit is (2 * 6), but as I know how the Elder Runes work I can use my Philosphae score. 6 * 4 allows me to open it in a season. I do not need to use the runes.
Leon.
Yes, as Brutus says.. you don't need to actually use Elder Runes.. it just enhances your knowledge of such.. though I'd say you should probably be using verditius runes at least.
I find this sudden thread revival amusing, seeing as just last session my Verditius made his own tower using the same spell.. along with the staff that makes it fly ^^