The Oostkerk was designed by Bartholomeus Drijfhout and Pieter Post and was built between 1648 and 1667. After Drijfhout died in 1651, the building was continued under the Leiden architect Arent van 's Gravezande, who had just completed the Marekerk in Leiden. The white organ was built by Gebr. de Rijckere from Kortrijk in 1782. Two stained glass windows from 1664 still exist in the church, and the klokkenstoel contains a bell by C. Noorden and one by J.A. de Grave, 1715.
References:Celje Castle was once the largest fortification on Slovenian territory. The first fortified building on the site (a Romanesque palace) was built in the first half of the 13th century by the Counts of Heunburg from Carinthia on the stony outcrop on the western side of the ridge where the castle stands. It had five sides, or four plus the southern side, which was a natural defence. The first written records of the castle date back to between 1125 and 1137; it was probably built by Count Gunter. In the western section of the castle, there was a building with several floors. Remains of the walls of this palatium have survived. In the eastern section, there was an enclosed courtyard with large water reservoirs. The eastern wall, which protects the castle from its most exposed side, was around three metres thicker than the rest of the curtain wall. The wall was topped with a parapet and protected walkway.