Helsinki's neoclassical buildings were often used as a backdrop for scenes set to take place in the Soviet Union in many Cold War era Hollywood movies, when filming in the USSR was not possible. Some of them include ''The Kremlin Letter'' (1970), ''Reds'' (1981), and ''Gorky Park'' (1983). Because some streetscapes were reminiscent of Leningrad's and Moscow's old buildings, they too were used in movie productions. At the same time the government secretly instructed Finnish officials not to extend assistance to such film projects. Rarely has Helsinki been represented on its own in films, most notably the 1967 British-American espionage thriller ''Billion Dollar Brain'', starring Michael Caine. The city has large amounts of underground areas such as shelters and tunnels, many used daily as swimming pool, church, water management, entertainment etc.