I've been toying - yet again - with Hermetic Architecture. I read the Sub Rosa article on it and found it wasn't great, it has numerous things in it where the numbers just simply don't add up to what it should be.
I'm aiming for making a Verditius since they get the best vis numbers out there. My goal is to build these buildings using normal means, not using Rego Terram directly (unless necessary).
Our game is going to be played with out Magis already having ten-years out of gauntlet under our belt before play.
I'm not fully familiar with the best way to build a hermetic architect, beyond saying that unless you expect a very long lasting game, I wouldn't create a magus at Gauntlet + 10 years geared towards that mystery. It's the kind of hobby that's nice to get when you approach the century past gauntlet, and even then it's a specialty. A verditius might be able to do it earlier with the right mysteries, but my intuition is that I wouldn't really try that before 50 years past the gauntlet.
But if you decide to go in that direction anyway, I'll give the following advice: Get a magical focus. I don't have my database right now, but my guess is hermetic architecture would fall under minor, while auras and regios would fall under major (could overlap with intellego vim spells and the RoP:M guidelines which are more accessible). And consider any virtue helping with lab totals, because the creo vim guidelines are really geared for "epic levels". The Muto and Rego effect are more accessible, however, and can be nice in the right locations. More than that, I'll let others comment.
My groups Saga is based around Hermetic Architecture manipulation of a Regio. I point that out because it was a core founding part of our game. We started off with books on varies subjects related to it, several spells (which we had no chance of casting anywhere close to the start of the saga), and a whole pile of research notes. There a fair bit of enchanted items setup around our Covenant that are specifically HA which could be studied.
Even with all that and a game that is fairly high powered, it was nearly a century into play before one of the Magi started messing with HA. As Temprobe said, it is something that is incredibly difficult and requires a whole lot of power. With a collection of roughly a century post gauntlet Magi, only one is really capable and he has a MMF that applies. It also tends to be extremely Vis expensive, even with the cost reduction you can get from a Verditius.
To build a Magus who can do a large part of the range (rather than a very narrow specialty) requires a range of high Arts, a high Magic Theory (to enchant the very expensive items), generally a Virtue or three which helps get totals up, and enough Vis to burn several rooks at a time. Near archmagi power level unless it is your pure focus.