Important tourist attractions in any city are museums. A number of museums that became world-wide known landmarks are constructed in many cities. These buildings usually stand out with its unique architecture and innovative technological solutions. The same concerns also to a number of alterations and extensions of historic buildings. The well-known transformation of the Louvre in Paris (1989) doubled a number of visitors. The National Gallery Singapore, created by rebuilding and connecting two important historic buildings (2008–2015), has become an active place of public venues and a very popular sightseeing.