In ecclesiastical architecture, a ciborium is a canopy or covering supported by columns, freestanding in the sanctuary, that stands over and covers the altar in a basilica or other church. It may also be known by the more general term of baldachin, though ciborium is often considered more correct for examples in churches. Really a baldachin should have a textile covering, or at least, as at Saint Peter's in Rome, imitate one. There are exceptions; Bernini's structure in Saint Peter's, Rome is always called the baldachin.

Hagia Sophia, officially the Hagia Sophia Grand Mosque, is a mosque, a former church, and a major cultural and historical site in Istanbul, Turkey. The last of three church buildings to be successively erected on the site by the Eastern Roman Empire, it was completed in 537 AD. The site was an Chalcedonian church from 360 AD to 1054, an Orthodox church following the Great Schism of 1054, and a Catholic church following the Fourth Crusade. It was reclaimed in 1261 and remained Eastern Orthodox until the fall of Constantinople in 1453. It served as a mosque until 1935, when it became a museum. In 2020, the site once again became a mosque.