Dubrovnik is the city of the highest historical and cultural value and of an outstanding artistic importance. The town fortifications, ramparts and towers outside the walls were built, reinforced and reconstructed in the period from the 12th to the second half of the 17th century. A number of constructors were involved in those works (Nicifor Ranjina in 1319, Mi-c-helozzo di Barth-ol-omeo in 1461-1464, Juraj Dalmatinac or George the Dalmatian in 1465-1466, Paskoje Milicevic in 1466-1516, Antonio Ferramolino in 1538, Mihajlo Hranjac, etc.). Dubrovnik had four town gates, the two of them toward the port and another two (with bascule bridges) toward the mainland. The ramparts around the town have been preserved in their original shape. They may be reached from below Luza Zvonara or going along the church of St. Salvatore on Poljana, a work by Paskoje Milicevic. From the entrance below Luza Zvonara, the way on the walls runs above the Street between the Gate of Ploce Since the ancient times, the centre of public life has been Luza Square. It continues toward the west into the main artery of the town core, the so-called Placa (Stradun). On the northern side of the square is the Sponza Palace, and in the middle of it the Orlando's Column from the 15th century, with a knights's statue, carved in stone. This was the place where all public announcements and proclamations but also public punishments were taking place.