A spacious entrance-hall, with two monuments, not executed in a very fine style of art, leads into the interior of the church, which is of considerable extent, but built in a very simple style.

The pillars, two of which always stand together, and the four royal monuments at the entrance, are all of Egyptian granite.

The finest part of the church is the chapel of St.Rosalia on the right, not far from the high altar; both its walls are decorated with large bas-reliefs in marble, beautifully executed: one of these represents the banishment of the plague, and the finding of St.Rosalia's bones.

A splendid pillar of lapis-lazuli, said to be the largest and finest specimen of this stone in existence, stands beside the high altar.
The two basins with raised figures at the entrance of the church also deserve notice.

The left side of the square is occupied by the episcopal palace, a building of no pretensions.
Santa Theresia is a small church, containing nothing remarkable except a splendid bas-relief in marble, representing the Holy Family, which an Englishman once offered to purchase for an immense sum.