Top 10 cities facts

Dispute between Sydney and Melbourne. Debates over Federation in the late 19th century were dominated by a long dispute over whether Sydney or Melbourne should be the national capital. A compromise was reached: the new capital would be built in New South Wales, at least 100 miles (160 km) from Sydney.

In Naples. Lying mostly underwater, Campi Flegrei comprises 24 craters. It is one of the largest volcanoes in the world, capable of producing VEI 7 (super-colossal) eruptions. Its most recent eruption of 1538 created a new hill, Monte Nuovo.

Madras. The renaming of cities in India started after the end of the British imperial period in 1947 and continues to date. Madras was changed to Chennai in 1994, but the old name is preserved in many institutions, like Madras Stock Exchange, Madras University and Madras High Court.

In Helsinki. These powerful icebreakers are docked for the summer season at the port of Helsinki. Almost all of Finland trade comes through the brackish Gulf of Finland, which freezes easily during winter.

Mecca. In its modern period, Mecca has seen tremendous expansion in size and infrastructure. Mecca has become one of the most cosmopolitan and diverse cities in the Muslim world, although non-Muslims are prohibited from entering the city.

It is the site of Muhammad's ascension to heaven. In Sunni Islam, Jerusalem is the third-holiest city, after Mecca and Medina. In Islamic tradition in 610 CE it became the first Qibla, the focal point for Muslim prayer (later moved by Muhammad to Mecca), and Muhammad made his Night Journey there ten years later, ascending to heaven where he speaks to God, according to the Quran.

Cape Town. The central area of Cape Town is called City Bowl. It is enclosed by near vertical cliffs of 1,000 m (3,300 ft) high Table Mountain, and Devil's Peak and Lion's Head on either side.

King of France. Louis IX (1214 – 1270) is the only canonised king of France, mostly due to his support and participation in the crusades. There are many places named after him, including the city of St. Louis, Missouri, and both the state and city of San Luis Potosí in Mexico.

San Sebastian lies on the coast of the Bay of Biscay, Atlantic Ocean. In 1863 the city was chosen by the Spanish monarchy to spend the summer following the French example of the near Biarritz. As the "wave baths" at La Concha conflicted with shipbuilding activity, shipyards relocated to Pasaia, a near bay formerly part of San Sebastian.

Hamburg's many streams, rivers and canals are crossed by some 2,500 bridges, more than London, Amsterdam and Venice put together. Hamburg has more bridges inside its city limits than any other city in the world. The longest one (picture above), Köhlbrandbrücke is 3940 metres long.