The chapel, originally dedicated to the Annunciation to the Virgin Mary, owes its current name to the unusually abundant use of mirrors in the decoration of the walls and vault. It was built at its own expense by the Latin Major Marian Congregation in 1722-1726. Thanks to its extraordinary interior, for which the builders chose an impressive combination of marble, mirrors, gilded stucco decoration, frescoes and paintings, the Mirror Chapel is one of the greatest gems of Clementinum. Since the mid-1930s, the Mirror Chapel has been used for more secular purposes.