The covered three-storey corridor was erected on massive pillars vaulted together on each storey. The original drawbridge over the Middle Ages moat was replaced by the stone construction during building stages in 1686, 1707, 1748 and 1765. The corridor in the lower storey connects the Masquerade Hall with the Castle Theater in Český Krumlov, and the Connecting Corridor located in the upper storey of the bridge enables passage up to the castle park.
Source:http://www.zamek-ceskykrumlov.eu/description-of-objects-within-the-castle/