In 2007 Ukraine occupied 8th place in Europe by the number of tourists visiting, according to the World Tourism Organization rankings. Ukraine has numerous tourist attractions: mountain ranges suitable for skiing, hiking and fishing: the Black Sea coastline as a popular summer destination; nature reserves of different ecosystems; churches, castle ruins and other architectural and park landmarks; various outdoor activity points. Kyiv, Lviv, Odessa and Kamyanets-Podilskyi are Ukraine's principal tourist centres each offering many historical landmarks as well as formidable hospitality infrastructure. Tourism used to be the mainstay of Crimea's economy but there has been a major fall in visitor numbers following the Russian annexation in 2014.