The old church of Helsinki was designed by famous architect C. L. Engel and completed in 1826. It was originally mentioned to be temporary church for the construction time of new cathedral in Senate Square.
When the old Ulrika Eleonora Church was demolished, the recovered building materials and part of the movables were auctioned but some of the furnishings including the pulpit, benches and chandeliers as well as the organ were relocated to the newly built church. These furnishings were however replaced over the years with the exception of the pulpit. A new 36 stop organ built by Per Larsson Åkermann was installed in 1869.
The altarpiece painted by Robert Wilhelm Ekman was initially commissioned for Helsinki Cathedral, but was instead placed in the Old Church in 1854.
The old park, called also as “the Plague Park” , surrounding the church was originally a cemetery. It’s name cames from the time of Great Wrath (1710), when many victims of plague were buried to the ground. The latest burial was made in 1919. At the northeast corner of park lies the tomb of merchant Johan Sederholm (1722-1805).
At weekends the church is popular place for weddings and other events.
Ängsö Castle was first named as "Engsev" in a royal charter by king Canute I of Sweden (r. 1167-1196), in which he stated that he had inherited the property after his father Eric IX of Sweden. Until 1272, it was owned by the Riseberga Abbey, and then taken over by Gregers Birgersson.
From 1475 until 1710, it was owned by the Sparre family. The current castle was built as a fortress by riksråd Bengt Fadersson Sparre in the 1480s. In 1522, Ängsö Castle was taken after a siege by king Gustav Vasa, since its owner, Fadersson's son Knut Bengtsson, sided with Christian II of Denmark. However, in 1538 it was given by the king to Bengtsson's daughter Hillevi Knutsdotter, who was married to Arvid Trolle.
In 1710, the castle was taken over by Carl Piper and Christina Piper. Ängsö Castle was owned by the Piper family from 1710 until 1971, and is now owned by the Westmanna foundation. The castle building itself was made into a museum in 1959 and was made a listed building in 1965. It is currently opened to visitors during the summers.
The castle is a cubical building in four stores made by stone and bricks. The lower parts is preserved from the middle ages. It was redecorated and expanded in the 1630s. The 4th storey as well as the roof is from the expansion of Carl Hårleman from 1740-41. It gained its current appearance in the 1740s.