In the early Middle Ages, there was an important ecclesiastical center of the Great Moravian Empire directly below Bratislava Castle. The so-called Great Moravian Basilica was built in the 9th century, when Bratislava played a central role in politics and the church as an important center of power and administration. The basilica was a representative sacred building that probably served as the main church of a fortified area. Today, none of the basilica's towering walls remain, but its foundations and floor plans, the remains of walls, and traces of other buildings, including a smaller church and an ossuary from the 11th to 12th centuries, are still visible. These remains have been made visible below the castle through archaeological reconstructions and ground markings. Colored stone settings illustrate the different construction phases and building types, enabling visitors to understand the structure of the early medieval complex.