After Rome was destroyed by the Visigoths in 410, Emperor Constantine the Great chose a small fishing village on the Bosphorus to become the new imperial capital. This small fishing village was inaugurated as Constantinople, what we now know as Istanbul. The Roman empire based in Constantinople is usually referred to as the Byzantine Empire.

There are many artefacts relating to the Byzantine Empire in Istanbul, but the Beetle's favourite is the Byzantine cisterns. If you've seen the James Bond movie, From Russia with Love, maybe you remember the scene where the redoubtable Mr Bond is rowing in a small boat through a forest of marble columns – this was filmed in Yerebatan Saray Sarniçi.

This cistern is thought to have been built in 532 AD, using marble columns recycled from Greek ruins in and around the Bosphorus. The water was routed from reservoirs around the Black Sea and transported via the Aqueduct of Valens. It was used as a backup for periods of drought or siege for the Great Palace. Historians believe that the cisterns were left largely untouched by the Ottomans, who preferred running, not stagnant, water, and the stored water ended up being used to water the Topkapi Gardens. The cistern was later left to collect silt and mud until it was cleaned by the Istanbul Municipality and opened to the public in 1987.

It is just one of many cisterns underneath modern day Istanbul, and the largest at 70 x 140 metres, (or 2.4 acres), and can hold 80,000 cubic metres – over 21 million US gallons). It is very grand and there are twelve rows of 28 columns each making an impressive total of 336 marble columns and you walk between the columns on a large boardwalk. At the far end of the walkway are two large Medusa heads in the north-western corner, one inverted and the other on its side; according to mythology, placing her this way caused her to turn herself into stone. Another theory is that turning her upside down neutralises her powers. There are some huge fish too in the water whose function is to aerate the water (and feed on tourists' handouts). There are signs giving details of classical concerts that take place in the cisterns. The Basilica Cistern was restored in 1980 for visitors.

There's also a café with wobbly metal tables and chairs and orange lighting adding to the subterranean feeling.

Yerebatan is in Sultanahmet Square, at the north-eastern end of the Hippodrome, just off Divan Yolu, and across the street from Ayasofya (Hagia Sophia). Opening hours: Daily 0900-1700. Admission: $3.50.