The Brandenburg Gate was built during the 18th century on the request of the then-Prussian King Frederick William II. Its neoclassical style, based on the Acropolis in Athens, was to mark this 'new Athens' on the river Spree. It was intended to be the monumental entry to the Unter den Linden Boulevard, which led to the royal residence of the Prussian monarchs. Because of this, any transit through the Gate was severely regulated by etiquette. Although the Gate has five passages, regular citizens were only allowed to pass through the two outermost arches; the central passage was reserved for the royal family and ambassadors from foreign courts on their way to visit and conduct official business at the royal palace.