The Assumption Cathedral is stationed in the center of the Tsarevets Castle. Its importance lies in the fact that it contains the remains of the Bulgarian Saint Michael (St. Mihail). It was built on the foundations of an earlier Christian church, dating from the late fifth and early sixth centuries, and represents a large basilica that was built in two stages: The first was at the beginning of the thirteenth century as a single church with a semi-cylindrical vault, and the second in the fourteenth century when it was extended and reconstructed. Three rooms were found on the southern wall of it, and in the middle of it there is a bell tower, a rare phenomenon in ecclesiastical architecture in the Balkans. This cathedral was decorated inside and out. Excavations have revealed many multicolored ornate paintings and thousands of pieces of murals in it.