Acropolis of Alatri site features

The acropolis of Alatri, known locally as the Civita, sits at the top of the hill the town is built on, about 500 m above sea level and in the middle of the historic centre. It is a rock ringed by walls of polygonal masonry -- the kind called cyclopean -- and entered by two gates, the Porta Maggiore and the Porta Minore, and by a ramp at the foot of which a portico once stood, of which some ruins remain. On the enclosure stand the co-cathedral of San Paolo and the bishop's palace.

The walls

They are built of several courses of polymorphic megaliths, quarried from this same hill and fitted perfectly together without lime or cement, and their perimeter encloses a trapezoidal area of 19,000 square metres. They reach their greatest height at the Pizzale, the south-east corner, which tapers as it rises and is made of fifteen great blocks set one on another. The cornerstone at its base carries a relief of a winged figure -- also read as a solar globe, which would make it a salute to the sun rising on that side.

Near the Porta Maggiore the wall opens into three large rectangular false doors, about 90 cm deep. They were built for the gods to pass through, on one reading; for others their function is still obscure.

The two gates

Both share a mathematical property: the ratio of height to base coincides, to a good approximation, with the golden section.

The Porta Maggiore, on the south side, is 4.5 m high and 2.68 wide, and carries a monolithic architrave of astonishing size -- 4.0 by 5.13 by 1.3 metres, estimated at 27 tonnes, second in Europe only to the Lion Gate at Mycenae. It was built together with the walls, as the way into the town. Holes still visible in it show it was closed by a gate or by beams. It opens into a dolmen gallery nearly 11 metres long. The stairway up to it is nineteenth-century work.

The Porta Minore, on the north side, is also called the Porta dei Falli or the Grotta del Seminario, and is far smaller at 2.12 by 1.16 metres. It gives onto a narrow ascending corridor, perfectly preserved, roofed by nine monoliths in progressive corbelling -- nine, like the months of a pregnancy -- a system otherwise paralleled only inside the pyramid at Egyptian Memphis. The second name comes from what is carved above the door: three phalli, now weathered, symbols of fertility. The passage is thought to have served pagan rites, the symbol being a good omen for anyone who climbed its stairway without once stopping. At the upper left there are inscriptions in Oscan.

The portico of Betilienus, and the ramp

Down the slope below the north side of the acropolis lie the remains of a portico that the censor Lucius Betilienus Varus had built in the second half of the second century BC, to connect the acropolis to the town's forum -- where the Piazza Santa Maria Maggiore now is. It was originally a long colonnaded temple-like structure; what survives is the last stretch, which ran up against the north wall of the sacred area, with part of its stylobate, its rainwater channelling and the bases of some of its columns. The route ended at the start of the ramp that is still the easiest way up to the acropolis. At the head of that ramp stands a limestone lion, found in 1816 among the ruins of the vanished church of Sant'Angelo in formis, which must originally have come from a late-Republican monumental tomb.

What is on top

The cathedral rests on the remains of an ancient altar, part of whose polygonal-masonry base is still visible under the north side of the basilica. The bishop's palace was rebuilt between 1337 and 1342 and held a prison in its cellars, and the walled garden beside it was a cemetery until 1846. In the twentieth century long rows of trees were planted across the surrounding esplanade, turning the acropolis into a park in the middle of the town, and a stone building was put up against the cathedral to conceal a water tank.

The architrave of the Porta Maggiore

A single stone 4.0 by 5.13 by 1.3 metres, estimated at 27 tonnes, over a doorway 4.5 m high and 2.68 wide -- second in Europe only to the Lion Gate at Mycenae. The holes still in it are where the gate or the closing beams went, and behind it runs a dolmen gallery almost 11 metres long.

The Porta Minore's corbelled roof

Nine monoliths in progressive corbelling over a narrow ascending corridor, perfectly preserved -- nine, the source notes, like the months of a pregnancy. The system is paralleled only inside the pyramid at Egyptian Memphis.

The three phalli, and the Oscan inscriptions

Carved above the Porta Minore and now weathered, symbols of fertility, and the reason the gate is also called the Porta dei Falli. The passage is thought to have served pagan rites, and the symbol was a good omen for anyone who climbed its stairway without once stopping. Look at the upper left of the gate for inscriptions in Oscan.

The three false doors

Near the Porta Maggiore, three large rectangular recesses about 90 cm deep open in the wall. They were built for the gods to pass through, on one reading; for others their purpose is still obscure.

The Pizzale

The south-east corner of the Alatri circuit, where the walls reach their greatest height: fifteen great blocks set one above another, tapering as they rise. The cornerstone at the base carries a relief of a winged figure, which has also been read as a solar globe and so as a salute to the sun rising on that side.

The golden-section gates

Both gates share a property that is either design or coincidence and has never been settled: the ratio of height to base coincides, to a good approximation, with the golden section.

The portico of Betilienus and the stone lion

Below the north wall, part of the stylobate, the rainwater channelling and some column bases of the colonnade the censor Lucius Betilienus Varus built in the second half of the second century BC to link the acropolis with the forum. At the top of the ramp it led to stands a limestone lion, recovered in 1816 from the ruins of the lost church of Sant'Angelo in formis and originally from a late-Republican monumental tomb.

The altar under the cathedral

Part of a polygonal-masonry base is still visible beneath the north side of the basilica -- the remains of an ancient altar the cathedral was built on top of.

The buried cistern

Found beside the Porta Maggiore during recent work on the via Gregoriana and then reburied. It is thought to be the lacus ad portam named in the epigraph of the censor Lucius Betilienus Varus, among the works he had carried out in the 2nd century B.C.