Discover Mausoleum of Santa Costanza

The Mausoleum of Santa Costanza is one of the most important monuments of late-antique architecture, and is among the first examples — together with the Lateran Baptistery — of a Christian building on a central plan with an ambulacrum, a passage corridor.

It was raised by a woman beside the church she had built. It was erected at the beginning of the 4th century by Costantina, or Costanza, daughter of the Emperor Constantine, close against the great cemeterial basilica she had had built at the underground cemetery which was the burial place of the martyr Agnes — an example of the integration between mausoleum and basilica in the Constantinian age. Its entrance is preceded by a narthex with two apses at the sides acting as the link with the great cemeterial basilica, as in the Mausoleum of Helena, built against the Constantinian basilica of Saints Marcellinus and Peter on the via Labicana, today via Casilina.

Its innovation is two circles inside each other. The most innovative characteristic consists of the two concentric circular spaces, derived from Roman models of temples, mausolea and nymphaea such as the Pantheon and the Mausoleum of Augustus — and in particular from the Martyrium of the Holy Sepulchre erected in Jerusalem by the Emperor Constantine and his mother Helena, a building destined to influence a great part of medieval architecture.

Inside, a dome rests on twelve pairs of columns. The interior — a circular corridor covered by a barrel vault and a central space — is surmounted by a dome of 22.50 m in diameter, bounded by twelve pairs of granite columns taken from an earlier building of the Roman period. Twelve arched windows light the central part. The dome's own mosaics were removed on the orders of Urban VIII (1623-1644) because they were seriously damaged, and in the end niche stands a copy of Costanza's red porphyry sarcophagus — the original is today in the Vatican Museums.

What survives overhead is the reason to come. The 4th-century mosaics on the vault of the corridor show geometric motifs, naturalistic scenes with fruit, flowers, peacocks, doves, and grape-harvest scenes — a typical case of the adaptation of pagan themes to the Christian tradition, which long caused the mausoleum to be identified with a temple of Bacchus. They are among the oldest monumental Christian mosaics surviving in Rome.

Its plan is the point. The most innovative characteristic of the Mausoleum of Santa Costanza consists of the two concentric circular spaces, which derive from Roman models of temples, mausolea and nymphaea such as the Pantheon and the Mausoleum of Augustus, and in particular from the Martyrium of the Holy Sepulchre erected in Jerusalem by the Emperor Constantine and his mother Helena — a building destined to influence a great part of medieval architecture.

It is among the first of its kind. Turismo Roma places it, together with the Lateran Baptistery, among the first examples of a Christian building on a central plan with an ambulacrum, and calls it one of the most important monuments of late-antique architecture.

Its structure is a corridor and a dome. The interior consists of a circular corridor covered by a barrel vault and a central space, surmounted by a dome of 22.50 m in diameter, delimited by twelve pairs of granite columns taken from an earlier building of the Roman period, with twelve arched windows lighting the centre.

Its entrance was designed to connect. The entrance is preceded by a narthex with two apses at the sides which act as the link with the great cemeterial basilica — the same arrangement as the Mausoleum of Helena beside the Constantinian basilica of Saints Marcellinus and Peter on the via Labicana.

And part of its decoration has been subtracted. The interior of the dome was covered with mosaics, later removed on the orders of Urban VIII because they were seriously damaged.

It was built as a tomb, against a church, by the woman who paid for both. Costantina, or Costanza, daughter of the Emperor Constantine, erected it at the beginning of the 4th century, close against the great cemeterial basilica she had had built at the underground cemetery that was the burial place of the martyr Agnes.

Its columns came from an older Roman building. The dome is delimited by twelve pairs of granite columns taken from an earlier building of the Roman period.

Its model was in Jerusalem. The two concentric circles derive from Roman temples, mausolea and nymphaea — the Pantheon, the Mausoleum of Augustus — and in particular from the Martyrium of the Holy Sepulchre erected in Jerusalem by the Emperor Constantine and his mother Helena.

Its decoration was finished in mosaic, twice over. The vault of the corridor carries the 4th-century mosaics; the interior of the dome was also covered with mosaics, removed by Urban VIII when they had become seriously damaged.

Its contents have been moved. The end niche holds a copy of Costanza's red porphyry sarcophagus; the original is today preserved in the Vatican Museums.

What are the opening hours? None are published. Turismo Roma says to consult the official site for access times and visit information.

How much does it cost? No price is published for the complex.

Who built it and when? Costantina, or Costanza, daughter of the Emperor Constantine, at the beginning of the 4th century, close against the great cemeterial basilica she had had built at the cemetery where the martyr Agnes was buried.

Why does its plan matter? It is among the first examples, with the Lateran Baptistery, of a Christian building on a central plan with an ambulacrum, and one of the most important monuments of late-antique architecture.

Where does that plan come from? From Roman models of temples, mausolea and nymphaea such as the Pantheon and the Mausoleum of Augustus, and in particular from the Martyrium of the Holy Sepulchre erected in Jerusalem by the Emperor Constantine and his mother Helena.

How big is the dome? 22.50 m in diameter, delimited by twelve pairs of granite columns taken from an earlier Roman building, with twelve arched windows lighting the centre.

What do the mosaics show? On the corridor vault, 4th-century work with geometric motifs, fruit, flowers, peacocks, doves and grape-harvest scenes; in the niches, the handing of the keys to Saint Peter and the handing of the law to Saints Peter and Paul; and at the sides of the entrance, Costanza and her husband Hannibalianus.

Why was it thought to be a temple of Bacchus? Because the mosaics are a typical case of the adaptation of pagan themes to the Christian tradition — the grape-harvest scenes above all.

Who were the Bent-vogels? A bizarre association of Dutch and Flemish artists who met here in the seventeenth century, toasting before the porphyry sarcophagus after baptism parties in an osteria on the via Nomentana; the celebrations could last three days and three nights, until Clement XI forbade the custom in 1720. Some of their names, carved in the ambulatory niches, can still be read.

Is the sarcophagus the real one? No — the end niche holds a copy; the original red porphyry sarcophagus is today in the Vatican Museums.

What happened to the dome mosaics? They were removed on the orders of Pope Urban VIII (1623-1644) because they were seriously damaged.

Who drew it? Antonio da Sangallo, Vignola and Piranesi, among others; their sketches bear witness to decorations now vanished.