Ukraine occupies 8th place in Europe by the number of tourists visiting, according to the World Tourism Organisation rankings, because of its numerous tourist attractions: mountain ranges suitable for skiing, hiking and fishing: the Black Seacoastline as a popular summer destination; nature reserves of different ecosystems; churches, castle ruins and other architectural and park landmarks; various outdoor activity points. Kiev, Lviv, Odessa and Kamyanets-Podilskyi are Ukraine's principal tourist centres each offering many historical landmarks as well as formidable hospitality infrastructure. The Seven Wonders of Ukraine and Seven Natural Wonders of Ukraine are the selection of the most important landmarks of Ukraine, chosen by the general public through an Internet-based vote.