The Neva is the youngest and one of the widest and most full-flowing rivers in Europe. Only 70 km long and about 10 m deep, it originated four or five thousand years ago from the site of a strait which connected the Litorino Sea and a very large Ladoga Ice Lake (the largest freshwater lake in Europe today.) By the gulf of Finland the river forks into armlets which, together with several tributaries, form an expansive delta. It was on the Neva Delta Islands that in 1703 Peter the Great founded the city of St Petersburg. In the late 19th century over 1000 islands were registered in the delta, which explains the fact that the city was dubbed the “Venice of the North”. Today the city lies on 42 islands, the largest being Vasilievsky (10.9 km2) and Petrogradsky (6.2 km2). A great number of bridges (about 400 – with those in the suburbs, eight of which span the River Neva) connecting the St Petersburg islands with one another has earned the city another name – “Museum of Bridges”. Best known are its drawbridges across the Neva which offer a great sight to see when opened during the white nights.