PETROVARADIN FORTRESS – sometimes called ‘’Gibraltar on the Danube” had been built between 1692 and 1780. It takes 112 acres, and is divided into the upper and a lower town. On the upper town, there are the bastions: Lower Ludwig’s bastion, Upper Ludwig’s bastion, Innocentie’s, Maria Theresa’s, St. Leopold’s and Tsar Joseph’s. Access is possible through the gates of: Ludwig, Leopold, Molinary, Karlo VI and Court gate. Some authentic places are still preserved like: Officer’s pavilion, Leopold powder magazine, Proviant magazine, Arsenal, the long barrack, the clock tower and a great wartime well. This whole complex was created according to the concept of marquis Sebastian Voban (1633-1707). Among the builders, the most prominent place is taken by an Italian count Alois Luigi Ferdinando Marsili (1659-1730). He was a versatile personality, highly educated writer, historian, cartographer, archeologist, architect, builder and soldier. He wrote a book on the Danube, published in The Hague in 1726 in which he shares some facts about Petrovaradin and Cenej (suburban part of Novi Sad). His legacy is held in Marsili Museum in Bologna, which exists since 1930.