Discover Castel Sant'Angelo

Castel Sant'Angelo — also the Mole Adriana and the Mausoleum of Hadrian — stands on the right bank of the Tiber a few steps from the Vatican, to which it is connected by the Passetto di Borgo. Turismo Roma calls it one of the most famous and most visited monuments in Rome; the reference work notes the structure was once the tallest building in Rome.

It was built to out-do a mausoleum. Turismo Roma dates its history to 135 AD, when Hadrian, wanting a tomb for himself and his family, turned to the architect Demetriano with a monumental tomb in mind in the style of the Mausoleum of Augustus but markedly larger. It was finished in 139 by Antoninus Pius, a year after Hadrian died. The reference work gives the span as 134 to 139.

The shape you see is the bottom of the original. The monument is a cubic base in Luni marble carrying a drum that now forms the lower part of the castle; the whole was clad in marble and decorated with festoons and friezes carrying the names of the emperors buried inside, and the summit held a bronze quadriga bearing Hadrian in triumph. The reference work adds a garden top.

Inside, the lining is gone and the fixings are not. A gallery round the drum leads to the burial chamber at the centre, once faced in precious polychrome marble — and the clamps that held those slabs can still be seen. Hadrian's ashes were here, with Vibia Sabina, Antoninus Pius and Faustina the Elder, and the emperors Commodus, Marcus Aurelius, Septimius Severus, Geta and Caracalla — the last recorded deposition being Caracalla in 217.

Then it stopped being a tomb. It was absorbed into the Aurelian walls and lost its original function — in 403, perhaps under Honorius, says Turismo Roma; in 401, says the reference work — and began to be called castellum. The urns and ashes were scattered by Visigoth looters during Alaric's sack of Rome in 410, and in 537 the original bronze and stone statuary was thrown down on the Goths besieging the city.

The name arrives with a plague. Around 590, during a procession to avert an epidemic that was decimating Rome, Pope Gregory I saw the archangel Michael sheathing his sword on top of the Mole. The plague ended; a church to Saint Michael followed, and later the statue of the angel putting away his sword.

The popes made it everything at once. Ceded by the Orsini to the Church in 1365, it served as refuge, seat of the Vatican Archive, a vault for the Treasure of the Church, a tribunal and a prison. Alexander VI had Antonio da Sangallo the Elder turn it into a true stronghold with four pentagonal bastions and a moat, and an apartment frescoed by Pinturicchio.

And the escape route worked twice. The Passetto, built under Niccolò III Orsini, carried Alexander VI out of the Vatican in 1494 ahead of Charles VIII's militias, and Clement VII in 1527 during the Sack of Rome.

It became a museum in 1925. Turismo Roma publishes no hours and no admission price, directing visitors to the Museo Nazionale di Castel Sant'Angelo's own page — and records that from its terraces you get one of the most striking panoramas of the city, above all at sunset.

A cube carrying a cylinder, and the cylinder is the tomb. Turismo Roma describes the monument as formed of a cubic base in Luni marble and a drum — a circular construction — which currently makes up the lower part of the castle. Everything above that line is later.

It was faced, not bare. The whole building was clad in marble and decorated with festoons and friezes on which could be read the names of the emperors buried inside. The reference work adds a garden top and a golden quadriga. The reference work also notes it was once the tallest building in Rome.

The interior is organised around a spiral. A gallery running around the drum gives onto a corridor leading to the burial chamber at the centre — a plan built for processing a body inward and upward rather than for circulation.

The stripping is legible. The burial chamber was decorated with precious polychrome marble slabs, and the clamps that held them can still be observed. The reference work records Vasari noting that stone columns were taken from the tomb of Hadrian to ennoble and decorate Saint Peter's, and that one survivor — the capstone of a funerary urn, probably Hadrian's — ended up at Saint Peter's covering the tomb of Otto II before being built into a Renaissance baptistery.

The military shape is Renaissance, not Roman. Antonio da Sangallo the Elder, for Alexander VI, built the four pentagonal bastions and the moat — angled outworks designed against cannon, wrapped round a second-century drum.

And the state rooms are a quotation. The Sala di Apollo was frescoed with grotesques by Perin del Vaga, who took his inspiration from the rooms of the Domus Aurea, decorated with cupids, griffins, satyrs and tritons.

It was commissioned to beat a specific rival. Turismo Roma records that Hadrian wanted a monumental tomb in the style of the Mausoleum of Augustus but of markedly greater dimensions, and turned to the architect Demetriano. Work began in 135 (Turismo Roma) or 134 (the reference work) and was finished in 139 by Antoninus Pius, a year after Hadrian's death.

Its approach was built with it. The reference work records that Hadrian also built the Pons Aelius facing straight onto the mausoleum — the bridge and the tomb are one design, which is why the view along it still works.

The conversion to a fortress was subtraction, not addition. Absorbed into the Aurelian Walls under Honorius, it lost its original function; much of the tomb's contents and decorations have been lost since. The statuary went in 537, thrown down upon the attacking Goths.

Then it was rebuilt as artillery. Antonio da Sangallo the Elder made it a true military stronghold for Alexander VI, adding the four pentagonal bastions and the moat.

And the last structural campaign reversed centuries of silting. Between 1933 and 1934 the castle was completely restored, with the moats and bastions reinstated and the ground outside the fortifications laid out as a garden.

What are the opening hours? Turismo Roma publishes none, saying only that information for the visit is on the page of the Museo Nazionale di Castel Sant'Angelo. Check that site — this page will not guess.

How much does it cost? No reachable authority publishes a price. Same answer, same reason.

What was it originally? Hadrian's mausoleum, for himself and his family, begun in 135 (Turismo Roma) or 134 (the reference work) and finished in 139 by Antoninus Pius.

Who is buried there? Hadrian, his wife Vibia Sabina, Antoninus Pius and Faustina the Elder, and the emperors Commodus, Marcus Aurelius, Septimius Severus, Geta and Caracalla — the last recorded deposition being Caracalla in 217. The ashes were scattered by Visigoths in 410.

When did it stop being a tomb? When it was taken into the Aurelian Walls — 401 says the reference work, 403 says Turismo Roma.

Why is it called Castel Sant'Angelo? Around 590, Pope Gregory I saw the archangel Michael sheathing his sword on top of it during a procession against a plague; the plague ended.

What is the Passetto? The covered corridor to the Vatican, which carried Alexander VI to safety in 1494 and Clement VII in 1527.

Who made the angels on the bridge? Bernini and his workshop, placed by Clement IX between 1667 and 1669. The first two, by Bernini himself, are now in Sant'Andrea delle Fratte.

Is the Tosca connection real? The opera is set here: Cavaradossi is shot in the courtyard and Tosca throws herself from the ramparts.

How long should I allow? About an hour and a half, plus the bridge.