Istanbul is the only major city located on two continents -- Europe and Asia. During its more almost 2,000-year history, it has been the capital of the Roman, Byzantine and Ottoman Empires.

The White Sea, in Russia, has the lowest temperature, only -2 degrees centigrade.

America's largest city (by landmass) is Yakutat, on a glacier-surrounded bay in southern Alaska. It may only have 660 residents, but it's six times as big as Rhode Island!

Lake Bosumtwi, situated within an ancient meteorite impact crater, is the only natural lake in Ghana. The Ashanti consider Bosumtwi a sacred lake. According to traditional belief, the souls of the dead come here to bid farewell to the god Asase Ya.

The Amazon River has over 1,100 tributaries, 17 of which are over 1,500 kilometres long.

Mount Etna of Italy is thought to be the world's oldest active volcano. The first record of its eruption dates back to 1500 BC. Since then, Etna has erupted 190 times.

Of the eight major islands in the Hawaiian Archipelago, Kaho'olawe is the only one that is uninhabited. It has always been sparsely populated due to its lack of fresh water, and was once used for target practice by the U.S. military.

The Seine River runs through Paris. The Seine flows 482 miles through France. The river begins in northeast France near Dijon and ends at the English Channel.

The Harz has a length of 110 kilometres (68 mi), stretching from the town of Seesen in the northwest to Eisleben in the east.

Nihoa, also known as Bird Island or Moku Manu, is the tallest of ten islands and atolls in the uninhabited Northwestern Hawaiian Islands. The island is home to 25 species of plants and several animals, making it the most diverse island in the entire NWHI.