The Solovetski Islands are located in the White Sea at the entrance of Onega Bay in Russia. Declared a natural and historical preserve in 1974, the islands offer a beautiful travel destination rich in history. The walls of the Solovetski Kremlin are 20 feet thick, to protect the monastery and the Gulag museum. (HÃ¥kan Ludwigson/Conde Nast Traveler)