The exterior of the church is a giant cube, reminiscent of early Italian Renaissance palazzi. The interior, though, is unlike anything else you have ever seen. To support the central dome, the architects created a pyramid of sorts with the use of columns taken from Nicopolis. They arranged them in tiers (even inserting some horizontally to the walls) that progressively narrow the area they would have to cover with the dome. This ingenious solution allowed them to get away with a dome diameter of 5.80 meters, instead of the 9 meters one would expect for a church of this size. But since what goes up, must come down, the weight of the dome proved too much for the columns. Many cracked or collapsed, necessitating the reinforcement of the walls that are much thicker today than originally planned.