I mean a tower isn't especially resistant to attacks or sieges. They stand out over the terrain and draw a ton of attention. They just seem like a really impractical sort of building. So why do so many wizards love making their covenants in the shapes of towers? I mean, yeah, there's a spell that makes a wizard's tower, but that just begs the question of why the author of that spell chose a tower in the first place. Does anyone know a good reason to make covenants in the shapes of towers?
Good view of the surrounding areas, defensible, and circular rooms are really good for Circle-style spells and such. Plus, mystical symbolism likes circles. Having a nice big lab and a personal room above or below it is nice.
Good reasons there. Plus it brings some Tolkien style into Ars Magica.
However, I've rarely had magi in towers. Sometimes, though. Depends on what's more convenient for the covenant.
Chapter 2 of GotF might provide a clue, in how it talks of the Roman limes and how "In the pagan days of the Empire, temples dedicated to Mercury were common in these frontier towns, and his priests worked their magic to strengthen the integrity of the Empire through a “barricade” of magically-linked temples along the boundary."
Wikipedia mentions the Limes Germanicus had 60 forts and 900 watchtowers.
Bonisagus cast the first ever Conjuring the Mystic Tower ritual at Durenmar (the site of a Temple of Mercury, IIRC) and Notatus invented the Aegis of the Hearth and first cast it there as well. Perhaps there was a deeper plan that didn't amount to anything. At least not yet, anyways.
My magus prefer bunkers. So i guess it's personal preferences all over the place.
Wizards love towers, because they believe that's where a wizard should live. See https://tvtropes.org/pmwiki/pmwiki.php/Main/MageTower for a huge list of mages in towers in literature and film. Every fantasy series has them, and since Dragonlance every version of D&D puts them in. Therefore, roleplayers (and roleplaying authors) follow the trope so their mystical wizards feel appropriately like fantasy wizards. This explains their appearance in early editions of Ars Magica.
The reason why they're prevalent in later editions of Ars Magica, where Mythic Europe tries to have a more historically accurate feel, is because the major surviving architecture of the 13th century is in the form of churches and towers. England and France have a lot of tower keeps, and German speaking lands have their bergfriede. There are also tower houses across Europe. The roleplayer looking for historic inspiration comes across lots of pictures of picturesque towers and they naturally occupy the mind as somewhere suitable for wealthy and powerful characters.
One other big factor is that Bonisagus put a tower up at Durenmar, and obviously lots of people copied the Founder. Blame whoever loved towers in Mark Rein Hagen's home saga.
Merlin has a tower in Sword in the Stone.
sight range spells
a person standing on the ground on level terrain can see 5 miles to the horizon, assuming they stand 5 foot tall. Each foot of rise above this gives approximately 1 mile (until we get to modern building heights, when the calculation is less about curvature and more about atmospheric conditions, which in bad weather may apply to the medieval towers as well, but I digress). If you have a spell with sight range, or a spell which affects vision for intelligo, a 30 foot tower gives you a 30 mile range advantage.
They also give a benefit (according to covenants) for aurum lab results.
It also raises you above the odor of the unwashed masses aka grogs and the poor sewage conditions of medieval architecture.
In modern fantasy and RPGs, it's probably because of Orthanc and/or any other interpretation as to which are The Two Towers.
Privacy - only a single door. Your lab is high up so some one blundering in would have had to blunder through the one (guarded) door, and up several levels in the tower. Very unlikely. This in turn is good for safety. If your tower was instead spread across ground level you'd have all sorts of windows and doors to guard from cheeky covenant children, drunks, casual thieves, etc.
Defence - With a few actually quite simple spells you can literally hold off an army with a tower. That single entry point, magically reinforced walls and an excellent sight line for attack spells. Very defensible.
Aesthetics - Towers have that badass, Freudian, long-how-big-my-dick-is feel to them. They dominate the skyline, require some serious nouse to build and can be very beautiful, especially magically created ones.
Space - Towers maximise space and minimise footprint. You can have a dozen towers surrounded by a curtain wall in a much smaller area than if they were al lair out at ground level. This in turn makes your neighbours less antsy. No massive castle, with huge courtyards to muster troops in.
Apart from phallic symbolism?
A tower is, in fact, quite resistant to sieges, especially since wizard towers are traditionally made of at least stone. Just think how the Keep, the centerpiece of castle architecture, is essentially large fortified tower. Before later castles evolved with complex walls, gate systems, etc., the idea was to have a sturdy, defensible building that can house a bunch of people.
Unless the attacker brings siege engines (which is a fairly large investment), a stone tower with a narrow stairwell can hold against fearsome odds.
Magic-wise? As mentioned, Vision-range spells. Also: good vantage point in general. good observatory spot. Ideal for Ring spells.
Culture-wise? It stresses the motif of isolation of erudites from the masses, as in "ivory tower". In European culture, it probably interfaces with the myth of babel, as a metaphor of some grand, world-changing pursuit.
Did I mention phallic symbolism?
One more reason related to the footprint: Aegis of the Hearth.
In Ars Magica, that minimal footprint takes an added dimension when you remember that the Aegis has a range of Boundary, which in ArM5 p.113 is defined as one hundred paces in diameter. (Note that in ArM4 the target Bound did not have that size limit. I don't have my ArM3 book at hand, but the base size for the spell was 100 feet, with added vis possible to increase that diameter.)
So a desire to enclose all of the covenant's most valuables (labs, library, vis, etc.) within a single Aegis (or in the most cost-effective one) means that using the vertical component of a tower is extremely valuable. Particularly in sagas that do not allow variations of the parameters of the spell without original research.
The same vertical element is also useful if your covenant is in a location that is physically limited, such as mountains or an island.
Finally, magical auras can be small in size, so a tower can help ensure that all the labs are located where the aura is highest.
Some will claim that an underground location offers the same benefits. That is correct in most cases, although it is harder to trace the boundary for casting the Aegis.
Towers also make it easier to see above/through the treeline to observe the heavens, puts some distance between you and the noises of the covenant, and most towers fall well within the guidelines for the base Structure target.
Personally, though, I'd redesign Conjure the Mystic Tower into something wider and squatter, as you end up with a lot more useful space than the standard spell.
In addition to the reasons mentioned, there is the utterly mundane reason that towers are expensive to build, therefore they show off wealth.
Some magi have particular reasons, such as specialising in Auram, which benefits from an elevated lab.
But, at the end of the day, I guess there are two kinds of magi. Those who want to show off build towers because they can. Those who want to go under the radar do not, because the tower doesn't ... go under any radar.
The Aegis is a great point, but I find myself wondering how other sagas deal with a covenant that's bigger than a single tower? do they design a bigger aegis, do they allow 'boundary' to expand further than normal, or do they resign themselves to not having an Aegis for a significant portion of their covenant grounds?
To be flatly honest, I did not reread the details since 3ed ...
100 paces across for boundary is quite big. Much bigger than a single tower. A mystic tower is only 10 paces across after all. You can put quite a few of them inside a boundary.
Well, you can carefully design your covenant to fill a standard Boundary. We did this several times in our sagas, once with a huge Roman style villa, another time with a hemispherical ice cave. There are several canonical covenants that wouldn't fit in a standard Aegis - Durenmar being one of them.
The alternative is to either maintain multiple Aegis spells or to design to only have the most important buildings under the Aegis - like an inner bailey of a castle. Not being able to increase the size of the Aegis is IMO one of the failings of 5th edition. If the Aegis effect had just been a ReVi guideline and the normal Aegis of the Hearth spell was the 'standard', magi could do more interesting things.
I always understood the bit about how you cannot reinvent the Aegis with different parameters to not include additional size.
In my saga I would a 100% allow people to add extra magnitudes to their Aegis to have it cover a bigger area, and I always assumed that is how a covenant like Durenmar is able to cover an entire valley in an Aegis. Apocryphally I would say that my interpretation is supported by the canon as otherwise most canonical covenants would not be able to fit even the laboratories/sancta within their Aegis.
As for your comments on Conjuring the mystic tower I wholeheartedly agree.
I have been doing some calculation for my own saga, and by my estimation the canon spell uses up only about 40% of the allowed volume of stone under conservative assumptions and the majority of that stone is taken up by the foundation.
I have been able to redesign in on paper to fit a square-base stone tower with a 14 by 14 meter base and 6 floors each of 4.5 meters in height (1 meter of that is taken up by the thickness of the floor). My tower has a surface area pr. floor that is just double that of the tower in the core book and is also 4 meters taller.
EDIT: I can see that I am sprouting a lot of numbers in referencing the design of the Conjuring the mystic tower. I have reached these numbers by using a spreadsheet and if there's any interest I am willing to write up my spread-sheet based Mystic tower calculator and share it here.