The Senate Square and its surroundings form a unique and cohesive example of Neoclassical architecture. The square is dominated by four buildings designed by Carl Ludvig Engel between 1822 and 1852: Helsinki Cathedral, the Government Palace, the main building of the University of Helsinki and the National Library of Finland. Helsinki Cathedral is arguably Finland's most famous and photographed building; it celebrated its 150th anniversary in 2002. The oldest stone building in Helsinki is the Sederholm House located on the southeast corner of the square. The main building of the City Museum can be found on the Sofiankatu museum street.
The Senate Square also hosts a sound installation called the Sound of the Senate Square. It is a modern version of the European glockenspiel and can be heard every day at 17:49 as it travels from one building to the next. The composition runs for 5 minutes and 18 seconds and is composed by Harri Viitanen and Jyrki Alakuijala.