The Renaissance city of the first half of the '500 is almost entirely preserved, for a circuit of about 11 km. With 20 bastions and six gates.
The Renaissance city was erected after Padua, in 1509 during the War of the League of Cambrai,
was temporarily occupied by the Maximilian of Austria imperial troops. The city was soon released, but the danger induced the Venice Senate to order the walls' complete overhaul.
Begun in 1523 by Bartolomeo d'Alviano, Serenissima's general captain, the work was continued by Michele Sammicheli, and in 1544 could be considered completed. The defensive system complex, ordered on walls and formidable ramparts, excellent for the military architecture of the time, mades Padua, in the opinion of contemporaries, an impregnable city.
Starting from Piazza Garibaldi, where there is the medieval Porta Altinate (1286), one of the three remainig of the city's oldest, with short sections of walls still visible at verious points of the Ponti Romani and Tito Livio rivers, then walk along via San Fermo (with the namesake church leaning against the city walls, best visible from the outside, from the Largo Europe and the Riviera Mugnai) until you reach the intersection with via Dante and then you get to the second medieval gate, Porta Ponte Molino, large pointed arch surmounted by a mighty tower, whose sides extend important traits of the curtain wall of Municipal period.
Buyond the bridge, on the right, the so-called Ezzelino Tower (XIII century) was the external defense of the medieval walls. Following Piazza Mazzini and Viale Codalunga you get to the Bastione della Gatta, so called because the defenders of Padua, in 1509, exposed to the besiegers, for mockery, a cat on a pike.
From here you can reach the Baluardi Moro I, Moro II degli Scalzi e Impossibile. Following the walls continue to Porta Savonarola, dedicated to Antonio Savonarola, winner of Ezzelino da Romano ad Arlesega. This splendid work, which plays on color contrasts between the Istria stone and gray trachyte, was built by Giovan Maria Falconetto in 1530. After the gate there is the Bastione Savonarola and just beyond the S. Prosdocimo Bastione. Continuing you meet the Porta S. Giovanni, another work by G.M. Falconetto and the namesake Bastione. Following via Cernaia, you encircle the Bastione Saracinesca and arrive, surpassing the Bastione della Catena (which blocked the entrance of water in the city), in view of the so-called Devil's Tower, the main rest of the defensive city of the Carrarese period.
From here, taking Riviera Paleocapa you will soon arrive at the Astronomical Observatory – La Specola, built by the Venetian Republic in 1767 on Torlonga, one of the ancient castle's towers, an imposing defensive structure of the early Middle Ages, enlarged by Ezzelino Romano and rebuilt by the Carraresi: on west side there is the third gate of the medieval walls, which gave access to the castle, while the nineteenth-century building now occupied by the Department of Astronomy, hides an important stretch of the curtain wall that reappears a little further and continues with various interruptions to the north along the Tronco Maestro canal.
Following instead the course of thw river to the south, past the Bastione Ghirlanda, you reach the bastione Alicorno (open to tours), extreme southern point of the defensive system of the '500.
After crossing the Park Trieste and crossed the Piazzale S. Croce you lead to the Porta S. Croce (1527), surmounted by S. Prosdocimo and S. Girolomo's statues, and the namesake Bastione (open to tours). Following the streets G. Bruno and A. Manzoni that offer on the left the complete view of Michele Sammicheli's walls, with two Bastioni, S. Giustina and S. Antonio, you get to Porta Pontecorvo (1517) also known as Porta Liviana, in honor of the Serenissima's general captain Bartolomeo d' Alviano.
Taking the pedestrian path, which crosses the entire block of hospitals, you reach Via Giustiniani, from here turn right to Via Gattamelata and then go along the same path to the left until the Bastione Cornaro, designed by Sammicheli in 1539-40. From here, by via Cornaro and then via S. Massimo, you reach the intersection with via Orus whcih offers a beautiful view of the old bridge of Graelle (the metal shutters of duty), at the confluence of the S. Chiara channel with the Piovego and Roncajette. At the end of via Orus, turn right and continue along via Fistomba and then cross the Ognissanti bridge, from where you have a beautiful view of the Bastioni Portello Nuovo, Castelnuovo (originally with river gate for military purposes) and Portello Vecchio (you can visit from via San Massimo).
From here, you take the Lungargine Piovego to Porta Venezia (already Ognissanti). It was built in 1519, perhaps on a design by Guglielmo Bergamasco, it has a nice prospect in Istrian stone surmounted by a clock tower. And it is popularly called Porta Portello because here there was a small river where the boats, travelig along the rivers and canals that linked Padua and its province and the lagoon of Venice, stopped. In front of the gate, over the bridge, there is still the shrine of S. Maria Barcaroli of 1790, where travelers attended mass before embarking on barges.
Continuing along the walls, past the Bastione Piccolo you enter in the Arena's Park, which has the namesake Bastione and then you get to the navigation lock and the Porta Contarine's little church (1723), ancient place of river traffic articulation: its bridge and one near the Grade del Carmine mark the water's exit from the city and once they were closed by metal shutters.