The Old Church of Helsinki is the oldest church in Helsinki city centre, completed in 1826 by the architect Carl Ludvig Engel. The Old Church was originally intended only as a temporary solution when the 18th century Ulrika Eleonora Church, which was replaced by Helsinki Cathedral, was demolished to make way for the Senate square. Due to the temporary character, the old church was built of wood and without bells. The Old Church is surrounded by the Old Church Park, which was a former cemetery.
The Helsinki Synagogue is an Ashkenazi synagogue built in 1906 by the architect Jac Ahrenberg (1847-1914). The exterior architecture of the three-storey building follows Art Nouveau, as well as the eclectic style common in Central Europe and England at the end of the 19th century. The interior has been exceptionally well preserved in its original appearance. There are rectangular concrete pillars with gilded Art Nouveau details in the capitals. The vertical supports of the gallery balustrades are also decorated with Art Nouveau style metal ornaments.
Temppeliaukio Church is a modernist monolithic stone church, completed in 1969. The church, carved into the rock, was designed by brothers Timo and Tuomo Suomalainen and is an outstanding example of architectural expressionism of the 1960s. It is made of granite stone which allows daylight to filter through the roof. Thanks to its acoustic properties, the church is a popular concert venue.