The architecture of most Capuchin friaries around Europe follows pretty much the same pattern. On the other hand, it is rare to find this architecture in North America.
I used to be a Capuchin, and lived in, stayed in, and visited, many Capuchin friaries in Slovakia, Czech Republic, Austria, Switzerland, Italy, and the United States. I also met many Capuchins from just about every country of the world.
To understand Capuchin architecture, one needs to understand how the Capuchins came to be.
Their roots go back to Giovanni Bernardone (1182-1226), better known as St. Francis of Assisi. He was the son of a very wealthy merchant. In his teens, Francis was moved by the plight of the poor, which, back then, was the majority of people.
Had he lived several centuries later, he would probably try to accomplish a series of social changes. But in his time, that was rather unthinkable. Instead, the only way he could think of to help the poor was to join them.
He embraced Lady Poverty, and started the Order of Friars Minor (Ordo Fratrum Minorum), or OFM, commonly known as the Franciscans.
Some time after St. Francis' death, some of the friars felt that the Order was slacking, that they were not following the Rule of St. Francis to the letter enough.
Not everyone agreed. The Order split into two branches: The Observants (those who wanted to reform) and the Conventuals (those who said no reform was necessary). Eventually, they split into two separate orders: Order of Friars Minor Convetuals (OFM Conv), and just plain Order of Friars Minor (OFM). It is kind of ironic that those that split away got to keep the original name, so even today when you say "Franciscan," chances are you are referring the Observants (except in Poland, where it refers to the Conventuals).
Anyway, some time later, some of the Observants felt that the Observants were no longer following the Rule strictly. They split off as Order of Friars Minor Capuchin (OFM Cap).
It is important to say, that the Capuchins came to be during the era of Protestant Reformation and Catholic Counter-Reformation, around the same time the Jesuits were born. The Capuchins and the Jesuits were seen as two sides of the same coin. Both were to bring the Protestants back to the Catholic Church. While the Jesuits were to work on Protestant intellectuals, the Capuchins' job was to bring back the common folks.
The Capuchins believe that poverty is their greatest calling (as do the other Franciscans). Additionally, the Capuchins wanted to lead a very austere life. For example, they would not shave, or even trim their beards. In some parts of the world they still do not, in others, they grow a neatly trimmed beard, in yet others, some shave, some don't.
The Capuchin architecture is designed along the lines of simplicity (a natural result of Holy Poverty) and austerity.
Most of Capuchin friaries in Europe are at least several hundred years old. Many were built during the baroque era. Their churches, then, are built in the style known as Capuchin Baroque. Baroque architecture was characterized by extravagant forms, as it existed toward the end of the feudal era, the era of complete decadence of the wealthy aristocrats who felt nothing for the poor masses (spawning the French Revolution, American Revolution, etc).
Well, Capuchin Baroque somehow managed to combine the simplicity of Capuchin architecture with baroque forms, resulting in something very unique, beautiful, and quite spiritual.
Anyway, Capuchin Baroque is only a minor part of Capuchin architecture, an interesting side effect essentially.
The basic principle of Capuchin architecture was to build the friary adjacent to a church. Remember, the Capuchins were born during Counter-Reformation. It was, therefore, essential to make any Capuchin church openly accessible by anyone at just about any time of day. You could never know when a heretic was ready to come back. So, the church had to be open and accessible.
But, at the same time, the Capuchins were quite a contemplative order. They wanted to have access to their church at all times, and they wanted to have it all for themselves.
For that purpose, classical European Capuchin churches contain a "small church behind the church" called the chorus. This is a smaller room (smaller than the main church, that is), right behind the main altar, separated from the main church by a wall (the same type of wall most Catholic churches have behind the main altar).
This room is typically just filled with regular church pews, facing the main altar. The altar, of course, is behind the wall. But there is always a big door, visible from the chorus, but not from the church (since the main altar blocks the view). Open the door, and you are "in" the church. You can kneel in front of the Eucharist, you can sit or kneel in the pew, pray, or meditate, all the time being "in" the church, while completely undisturbed by outside visitors and undisturbing to them.
Naturally, the church alone was not enough: You have to have a room to live, you need a bathroom, a place to eat, as well as a kitchen. In other words, you need a friary. The friary is typically located behind the church, though in some cases it can be located alongside the church, at least partly so.
Every friary has a refectory, which is a fancy Latin name for a dining room. The tables in the refectory are arranged in a formal way. The guardian (head of the friary) sits at a separate head table from which he can see everyone else. If the friary happens to be the residence of the Minister Provincial (the head of the Province, typically a territory the size of a European country or region within a country, or several US states), then the Provincial also sits at the head table. Any visitors are typically seated at the head table as well, though sometimes they are seated with the rest of the friars (but typically close to the head table).
The rest of the friars sit at the rest of the tables, each having a fixed place to sit (though, in the US you typically do not have a fixed place assigned anymore).
The refectory is usually located on the ground floor. There usually are several floors above, with rooms (called cells) for individual friars (each friar living by himself), and of course with bathrooms and other single bare necessities of life.
There usually is a wide stoney staircase. Elevators are rare, though the Capuchin friary in Lucerne has one -- but you are discouraged from using it unless you are disabled.
The hallways and staircases tend to be wide, spacey, and dark. There is typically very little light (the friary in Vienna was a real pain for this!). You push a button to start it, and it lights up a little for a minute or two. While living in Vienna, I typically had to push the button three times on my way from the refectory to my cell. I was once caught by Father Secretary (Provincial Secretary) who was quite upset over my lack of the spirit of poverty. I objected that how was I supposed to unlock my door without seeing the lock. The miser actually showed me a special technique of inserting the key into the lock without hesitation in absolute darkness. It actually comes quite handy in the real life every so often.
Sometimes, a Capuchin friary has a crypt. In that case, its purpose usually defies the imagination of the best gothic writer. For example, I already described the Capuchin Boneyard in its own node.
The crypt of the Capuchin friary in Vienna is the burial site of the Emperors of Austria. Some have very simple coffins, some have them very elaborate. Maria Theresa has the biggest and fanciest of all. Furthermore, there is a dome above her, with a small window that opens inside the friary, right inside the hallway that leads to the shower room. Every time I went to take a shower, I walked by that window and took a glance at the fancy grave! I wonder if that was the reason that, during the six months I spent there, I never ever found anyone else in the shower room. Spooky!
Well now, all of this needs to be connected somehow. The typical European Capuchin friary has a long connecting hallway which runs alongside the longest wall of the church. It lets you go to the friary from the outside, ot the chorus from the friary, or anywhere from anywhere within the compound.
The front facade usually has a main church gate leading to the church. Next to it is the door to the connecting hallway (the door is heavy, just like the church gate). While the church gate is left open during the day, the door to the connecting hallway is kept locked at all times. In a typical friary, the connecting hallway is empty, it just leads to another door, which is where the actually friary begins (and, of course, has other doors along the way, to the chorus, crypt, etc.). The friary of Lucerne is quite unique in that it does not just have a dark, empty, connecting hallway, but a nice entrance directly to the friary (the entrance is still at the side of the church gate).
All in all, the traditional Capuchin architecture is very much like a medieval castle. Like a castle, it separates its inhabitants from the outside world with thick stoney walls and heavy gates/doors. Unlike a medieval castle, it is not designed for the life of luxury but for that of austerity and institutional poverty.
Strangely enough, having lived there for some time, I independently came to the same conclusion the Buddha made 2500 years earlier, namely, that austerity and asceticism do not lead to emancipation and enlightenment. It was much easier for me to grow and mature spiritually after I left the Order.