The current basilica was rebuilt in one campaign by Cardinal Anastasius, ca 1099-ca. 1120. A now-outdated hypothesis held that the original church had burned out during the Norman sack of the city under Robert Guiscard in 1084, but no evidence of fire damage in the lower basilica has been found to date. One possible explanation is that the lower basilica was filled in and the new church built on top due to the close association of the lower structure with the imperial opposition pope ("antipope") Clement III / Wibert of Ravenna. [13] Today, it is one of the most richly adorned churches in Rome. The ceremonial entrance (a side entrance is ordinarily used today) is through an atrium (B on plan) surrounded by arcades, which now serves as a cloister, with conventual buildings surrounding it. Fronting the atrium is the chaste facade of Carlo Stefano Fontana (nephew of Carlo Fontana), supported on antique columns, and his little campanile (illustration). The basilica church behind it is in three naves divided by arcades on ancient marble or granite columns, with Cosmatesque inlaid paving. The 12th-century schola cantorum (E on plan) incorporates marble elements from the original basilica. Behind it, in the presbytery is a ciborium (H on plan) raised on four gray-violet columns over the shrine of Clement in the crypt below. The episcopal seat stands in the apse, which is covered with mosaics on the theme of the Triumph of the Cross that are a high point of Roman 12th century mosaics.
