Basilica of Santa Prassede site features

You will walk past the door. Santa Prassede has no square in front of it and no facade on show: the entrance is a plain opening in a wall on a narrow street behind Santa Maria Maggiore, one shop-front wide, with nothing to say what is inside.

Through it, the church is a three-aisled basilica, broad and dim, with the aisles separated by piers and the nave running straight to the far end. The eye goes there immediately, because the apse is gold: a half-dome of mosaic with a standing figure at the centre and a tall figure on either side of him, set against a flat gold ground with a band of dark blue below. On the arch in front of it, two ranks of small standing men, twelve to a side, each holding up a circlet.

Set in the pavement partway down is a dark red stone disc, polished, about the size of a manhole cover — the one thing on the floor that is not floor.

The room you came for is on the right, a few paces in, behind a low doorway framed by two ancient columns; it is easy to walk past that too. Inside is a square chamber about four paces across, with no window, and every surface of it — the four walls and the vault above — is covered in mosaic on gold. Standing figures in white and ochre robes fill the walls shoulder to shoulder. On the vault, four angels stand on the corners and reach up to hold a circular medallion containing a single head and shoulders, so the whole ceiling is one gesture carried by four figures. There is no daylight; what the gold does is done with whatever light comes in through the door behind you, which is why the room repays standing still in it.

The Chapel of San Zeno

Paschal I's funerary chapel for his mother Theodora, and what Turismo Roma calls the most significant Byzantine monument preserved in Rome. Mosaics of saints on the walls; the Saviour in a medallion on the vault. A small windowless room, read slowly.

The apse mosaic

Jesus in the centre, flanked by Saints Peter and Paul, from Paschal's campaign of about 828.

The apsidal arch

Twelve men on each side holding wreaths of victory.

The porphyry disc

Set in the floor, marking a well where, by legend, Saint Prassede collected the remains and blood of martyrs.

The column of the flagellation

Brought to Rome by Cardinal Giovanni Colonna in 1223. The reference work notes that medieval relics of this kind lack indisputable authenticity, there being no forensic evidence.

Bernini's bust of Bishop Santoni

Giovanni Battista Santoni died in 1592; the bust is dated to about 1612 and is described by Turismo Roma as Bernini's first sculptural work.