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:Visby Cathedral (also known as St. Mary’s Church) is the only survived medieval church in Visby. It was originally built for German merchants and inaugurated in 1225. Around the year 1350 the church was enlarged and converted into a basilica. The two-storey magazine was also added then above the nave as a warehouse for merchants.
Following the Reformation, the church was transformed into a parish church for the town of Visby. All other churches were abandoned. Shortly after the Reformation, in 1572, Gotland was made into its own Diocese, and the church designated its cathedral.
There is not much left of the original interior. The font is made of local red marble in the 13th century. The pulpit was made in Lübeck in 1684. There are 400 graves under the church floor.