The Brandenburger Tor is a former city gate, located west of the city center. The city gate was one of the formal entries which led into the city. Nowadays the gate is the monumental entry to 'Unter den Linden', a famous boulevard of Linden trees. The Brandenburger Tor was commissioned by King Frederick William II of Prussia as a sign of peace and built by Karl Gotthard Langhans from 1788 to 1791. Today, it is considered one of Europe's most famous landmarks.