St. Casimir’s Church was founded by the Jesuits and dedicated to Lithuania’s patron saint Prince Casimir Jagiellon (1458-1484). The construction of the glorious building began in 1604 and was completed in 1635. Burnt to the ground just 20 years later when the Russians invaded in 1655, conflagration visited twice again within the next century in 1709 and 1749 before the architect, mathematician and astronomer Tomas Žebrauskas (Pol. Thomas Zubrówka, 1714-1758) restored it to more or less the form it's seen in today.
Over the centuries the church fell into the hands of the Augustinians, Napoleon’s Grande Armée, the Russian Orthodox Church (who significantly altered its appearance), the Lutherans (who used it as the garrison church for the occupying German Army during WWI) and others, including the Soviets who turned the whole place into a museum of atheism no less. Returned to the Catholic Church in 1988, the building was consecrated in 1991 and has since undergone a massive renovation project, restoring its predominantly Baroque style with Gothic and Renaissance touches. Of particular interest inside are three late Baroque altars and a recently discovered 17th-century crypt containing dark bas-reliefs featuring miscellaneous religious motifs.
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.