Alba Iulia Stronghold was built in the 1714-1738 being deemed one of the most representative Vauban stronghold in our country. The plan of the stronghold was accomplished by the Italian architect Giovanni Morando Visconti under the coordination of general Stefan of Steinville, which was then completed by general Weiss.The initial works started on the 4th of November 1715 when the groundbreaking ceremony of the bastion Carol was arranged, dedicated to the emperor , located on the North side pof the stronghold.The stronghold was identified in Weiss’s design as “The Main Stronghold in Alba Iulia, Transylvania”. Betewwn the XVIII-XIX centuries, the stronghold was the military center of Transylvania and a general military equipment storage. The walls perimeter is approx. 12 km, being built by 20,000 bondmen. The stronghold comprises 7 bastions (Eugeniu of Savoy, St.Stefan, Trinity, St. Mihail, St. Carol, St. Capistrano, St. Elisabeth) thus generating a star shape, characteristic for this kind of strongholds.The greatest bastion is Trinity, 116 x 115 m which has a blazon on the center.The walls are built of burned bricks, career rock or from the ruins of the Roman stronghold, the thickness of the walls at the basis is 3 m and on top 1.2 , supported by buttress in order to neutralize the soil force.
The entrance in the stronghold is done through 6 gates decorated with statues accomplished by a team of sculptors coordinated by Johhan Konig. The design and the construction works determined the modification of the street view, so that the gates were built – three facing the city and another three facing the instruction field on the West side.The stronghold is impressive because of the decoration elements and the beauty of the six gates of the fortification, which are unique in the entire European military architecture. No doubt the inspiration source of the artist is the antique mythology, decoration being accomplished by sculptors as Johann Konig, Johann Vischer and Giuseppe Tencalla. Between the walls of this stronghold major historic events of great importance for the history of Romania: the epilog of the Horea insurrection and the Great Unification of Transylvania with Romania on the 1st of December 1918.