Petrovaradin Fortress

Petrovaradin Fortress (Serbian: Петроварадинска тврђава, Petrovaradinska tvrđava, pronounced [pɛtrɔv̞arǎdiːnskaː tv̞ř̩dʑav̞a], Hungarian: Péterváradi vár) is a fortress in the town of Petrovaradin, itself part of the City of Novi Sad, Serbia. It is located on the right bank of the Danube river. The cornerstone of the present-day southern part of the fortress was laid on 18 October 1692 by Charles Eugène de Croÿ. Petrovaradin Fortress has many underground tunnels as well as 16 km of uncollapsed underground countermine system.

• http://en.wikipedia.org/wiki/Petrovaradin Fortress