The Piarist Church, also known as the Church of Maria Treu, is a Baroque parish church of the Order of the Piarists in Vienna. The church has eight chapels and is decorated with frescoes made by Franz Anton Maulbertsch in 1752–53. Commissioned by the Piarists, Haydn’s Missa in Tempore Belli (Mass in Time of War, sometimes known as Kettledrum Mass) was first performed here on 26 December 1796. The Piaristenkirche was elevated to the rank of Basilica Minor in 1949.
References:First record of Kastelholma (or Kastelholm) castle is from the year 1388 in the contract of Queen Margaret I of Denmark, where a large portion of the inheritance of Bo Jonsson Grip was given to the queen. The heyday of the castle was in the 15th and 16th centuries when it was administrated by Danish and Swedish kings and stewards of the realms. Kastelhoma was expanded and enhanced several times.
In the end of 16th century castle was owned by the previous queen Catherine Jagellon (Stenbock), an enemy of the King of Sweden Eric XIV. King Eric conquered Kastelholma in 1599 and all defending officers were taken to Turku and executed. The castle was damaged under the siege and it took 30 years to renovate it.
In 1634 Åland was joined with the County of Åbo and Björneborg and Kastelholma lost its administrative status.