More pagan temple than church, it served as a mausoleum for the cultivated but cruel tyrant, Sigismondo Malatesta, and his mistress (later wife), Isotta degli Atti.
It is considered as being more of a temple than an actual church.
A Prado annex, the Casen del Buen Retiro, up the hill in calle de Felipe IV, houses a collection of 19th-century paintings, but remained closed for renovations in 2000.