Top 10 cities of Europe facts

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.

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.

Vienna and Bratislava. Bratislava is only 60 kilometers (37.3 mi) from the Austrian capital Vienna. Before the Second World War, there was a regular fast tram service between the two.

Oslo. In 1624, during the reign of King Christian IV the city was destroyed by a fire. It was rebuilt and renamed Christiania in the king's honor. Following a spelling reform, it was known as Kristiania from 1877 to 1925, when its original name was restored.

It was destroyed by earthquake. The convent was ruined in the 1755 Great Lisbon Earthquake, which destroyed the city, killed possibly 100.000 of its inhabitants and disrupted the colonial ambitions of Portugal. The church was left unrestored to remind the tragedy.

Stockholm. In the 12th century, the Malaren Bay, a major trade route into central Sweden, was cut off the Baltic Sea as a result of post-glacial rebound of Scandinavia. The trade ships had to unload the cargo in the bay mouth that became too shallow to sail, which led to foundation of Stockholm at this place. Today, Malaren Lake is 0.7 m above sea level.

Belgrade is the capital city of Serbia as it is the seat of the country's government. Belgrade is also the largest city in the country, occupying an area of 138.98 square miles and having a population of over 1.166 million inhabitants. Belgrade is the economic hub of Serbia, with most local companies found in the city. Belgrade is also the cultural heart of the country and hosts many important cultural events

Hamburg, with its 1.7 Million of inhabitants, is the second largest city after Berlin (3.4 Million). The largest urban area in Germany is the Rhine-Ruhr metropolitan region with 11M.

In Bilbao. One of the most admired works of contemporary architecture, The Guggenheim Museum Bilbao was opened in 1997. Computer simulations of the building's structure made it feasible to build shapes that architects of earlier eras would have found nearly impossible to construct

Istanbul. The city is easily recognizable due to the Bosphorus strait dividing it into two parts located on different continents. Istanbul's commercial and historical center is situated in Europe, while one third of its population live in Asia.