Secret Rome.
10 discoveries.

The open circle at the top of the dome is called the oculus. It brings in daylight and, when it rains, water too: there is no glass covering it. The floor has 22 small drainage holes that let the water flow away.

After looking up, examine the marble below the opening. Those holes show how this monumental space deals with a very practical problem: rain falling inside the building.

Before the high river embankments, the Tiber could flood streets well beyond its banks. On the basilica’s façade, towards Via di Sant’Eustachio, a plaque records the flood of 5 December 1495 and the level the water reached.

Look at it from the square and compare it with street level. This small marker makes an otherwise hard-to-imagine part of Rome’s history visible.

Behind the entrance on Piazza Sant’Agostino is a grand hall lined with wooden bookshelves: the Vanvitellian hall, the monumental heart of Biblioteca Angelica. Notice how the books fill the walls high above you.

The library also kept works on the Index, the Church’s list of prohibited books, under special papal permission. That history gives the shelves another meaning: some of the books they held were not freely available for everyone to read.

From Via del Banco di Santo Spirito, enter the short Arco dei Banchi passage. The surprise is overhead: a blue vault dotted with painted stars turns a few metres between buildings into a miniature sky.

Beneath the arch, a plaque also records the Tiber flood of 7 November 1277. Look for it before leaving: this one passage holds both a decorative detail to photograph and a trace of the river’s history.

From its entrance, Borromini’s colonnade seems to stretch far beyond its actual length of less than nine metres. The trick is forced perspective: the space narrows towards the back, making nearby objects appear distant.

The warrior statue helps create the effect. It looks life-sized but is only about 90 centimetres tall. View it from the museum’s designated position and compare your first impression with those measurements.

At the corner of Via Santo Stefano del Cacco stands a left marble foot over a metre long, still wearing its carved sandal. The rest of the statue is lost: this fragment was just one small part of a colossal figure.

It was probably connected to the nearby sanctuary of Isis and Serapis, deities of Egyptian origin. Look at the sandal and imagine how large its wearer would have been.

Set into the wall of the Sapienza building, this little fountain tells the street’s story. The four books recall the university’s former home, while the deer’s head represents the Sant’Eustachio district. Even the water seems to flow from the pages.

There is a mistake to spot: the inscription labels the district IV, although Sant’Eustachio is district VIII. That small error turns a fountain stop into a miniature puzzle.

This weathered sculpture near Piazza Navona is one of Rome’s “talking statues”. From the sixteenth century, Romans left anonymous verses and messages on these statues to criticise powerful figures without signing their names.

The satirical messages associated with Pasquino became known as “pasquinate”. Its voice was made of paper rather than sound: imagine this marble figure as a public noticeboard for protest, long before social media.

Palazzo Altemps is known for its ancient sculptures, but the rooms deserve attention too. On the main floor, the painted loggia is decorated as an imaginary garden. The paintings bring nature into the palace and frame its collection of antiquities.

Before moving on to the next sculpture, pause to examine the walls and ceiling. They show how the residence was designed to impress through the setting as well as the artworks.

In little Piazza Mattei, four bronze figures seem to help turtles reach the upper basin. The surprising detail is that the animals that give the fountain its name were not part of the original design: they were added during the restoration of 1658–59.

Look first at the dolphins below, then at the turtles above the hands. It appears to be one continuous scene, but it was created through work carried out at different times.