First church in Paltaniemi was built in 1599, but it was destroyed by the very unusual earthquake in 1626. The next one was completed in 1665, but again it was destroyed by the Russian forces during the Greath Wrath in 1716. The current wooden church was built in 1726. Probably the oldest artifact inside the Paltainiemi church is the altarpiece from the year 1727. Famous paintings on the ceiling and walls was made by Emanuel Granberg in 1778-1781. The large painting on the rear wall, the “Final Judgement”, was once considered so shocking that the lower portion of the painting was removed – apparently even with an axe in places.
Outside the church are memorials to the Kalevala and the years of famine. The church is open to visitors daily throughout the summer.
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.