Key ring with engraved Zindan gate from Kalemegdan

In front of the Eastern (Despot's) Gate of the Upper Town in the middle of the 15th century, an outer semicircular fortress was built - the Zindan Gate complex. Zindan gate complex consists of arched gates with two round towers flanking the gate and bridge. The gate has a massive door studded with iron and utility rooms. Zindan towers are identical in form and purpose, but they do not communicate with each other. The upper part of the tower ended with a pinch, due to specially made huts of so-called muharabiya (meaning "nose for tar") or masquerade, which were very efficient and functional in the rejection of the enemy. Basements of the towers, apparently, the Turks used as dungeons for Christians. Turkish word zindan means dungeon.