Classic Sailing Amsterdam is located at fortress Kudelstaart, a beautiful place at the borders of the Westeinder Lake. Fortress Kudelstaart is one of the armed forts of the defence line around the Dutch capital Amsterdam. This defence line was built between 1883 and 1920. It is the only fortification that is based on the principle of controlling the waters around a city. It contains a network of 45 armed forts and can temporarily flood polders extending 135 kilometers around Amsterdam. The Defence line of Amsterdam (in Dutch "de stelling van Amsterdam") is inscribed on the UNESCO World Heritage List.