The Rector's Palace is a Renaissance apartment building built by the Republic of Dubrovnik when, at the end of the 15th century, the Grand Council decided that the prince of Mljet would no longer be elected outside the island but would be elected from the local population. Inside the prince's court is a spacious courtyard with a terrace and a well in front of it. A fort called the citadel was erected on the southeast side. There was a permanent guard at this place, who guarded the entrance to the Church and the churches of St. Pankration and St. Vlach, as well as towards the settlement itself. From there, they watched the Mljet Channel and the open sea. If they noticed other warships or pirate ships, they would immediately notify the guard leader and the prince about informing the locals about the need to secure the island and its inhabitants. If necessary, the news was reported to Prince Sipan by rowing boats from Sobra, which he then transmitted to the Prince and the Government of the Republic to Dubrovnik.