The Cathedral of St. Mary the Great is a catholic church and fortress built in the fifteenth century, which preserves a Romanesque appearance.
Its facade is flanked by two large towers topped by battlements and highlights its beautiful Gothic portal with archivolts with sculpted scenes from the Passion of Christ and sculptures of the Apostles. It is a Romanesque church with a Latin cross and inside is separated by three arches supported on pillars ships. It is classified as Imóvel of Public Interesse.
Inside, are the chapels of St. Bernard (by Fernão Brandão) and the chapel of the Blessed Sacrament, attributed to stonemason, João Lopes the 'old'.
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.