Lithuania, PlokÅ¡āiai, August, 2020. The entrance of PlokÅ¡tinā— missile base. In September 1960, the Soviet Union started the rapid construction of an underground military base. It was one of the first in the Soviet Union, near the village of PlokÅ¡āiai in the Lithuanian SSR. In 1960, more than 10,000 Soviet soldiers started to secretly work in the Žemaitija National Park for over two years. The base was regarded as one of the top Soviet military secrets, only to be revealed by U.S. reconnaissance in 1978. The PlokÅ¡tinā— nuclear missile launch site started operating around three years after it was established. Lithuanians discovered the existence of the base only after the URSS military forcer left the country. After twelve years of operations, the site was shut down. After the collapse of the Soviet Union, the site was abandoned and not maintained, now hosts the Cold War Museum, opening one of the four existing silos for visitors.