Fortifications were a manifestation of the importance of a medieval city. They reflected the military power of the city and its role and function in the defence system of the country.
The earliest mention of defensive walls in Poznań is in a document issued by Władysław the Elbow-high in 1297. It is assumed that the city was fortified by Przemysł II, most certainly in 1275. The length of the walls was 2300 steps (1 step = 75 cm) and the enclosed space measured around 21 hectares. The height of the wall approached 11 metres and it was supplemented by c. 35 towers. The towers had their names; some of them were maintained by various craft guilds and named accordingly (for instance, the Tailors' Tower, the Butchers' Tower) or named after other users (for example, the Dominican Tower). The city could be accessed through four gateways: the Wroniecka Gate from the north, the Wielka Gate and Wodna Gated from the east and the Wrocławska Gate from the south. There were also several smaller pedestrian gates cut in the walls, mostly in the 15th and 16th centuries. The distances between the gates are also known: there were 400 steps from the Wrocławska Gate to the Wodna Gate, 200 steps from the Wodna Gate to the Wielka Gate and 500 steps from the Wielka Gate to the Wroniecka Gate.
With the development of warfare technology the defensive system of the city was modified several times and eventually completed in the early sixteenth century. The medieval fortification in Poznań can be seen on a print by Braun and Hogenberg from 1618 which has been used for a 1:150 scale model displayed in the cellars of the Franciscan Church. In the 17th and 18th centuries the city walls became obsolete. Destroyed in numerous wars, they were occasionally repaired and even reinforced but they severely limited the growth of the city. The dismantling of the fortifications commenced by the Prussians in 1797 continued until the mid-nineteenth century.
Nowadays, only some remains of old fortifications can be seen. The best preserved example of the old city walls is the tower in Masztalarska Street and 23 Lutego Street. The tower is 6 metres high and 8.5 metres in diameter; the walls are almost 1.5 metre thick. It was equipped with eight arrow loops. From the yard of the fire station in Wolnica Street one can see the recently discovered and partly reconstructed fragment of the inner wall and the Catherines' Tower. The tower survived to the present day only because it was ecclesiastical property and part of the former convent of the Catherine nuns (presently, the Salesian Society). Extensive restoration work is being carried out and the fire station is now open to tourists who can see the tower and the reconstructed fragment of the city wall in all their splendour. A piece of the city walls can also be seen in Ludgardy Street. Between Chopin Park and Wrocławska Street (where the gateway towards Wrocław once stood) there is a fragment of the city walls with embrasures. They were built in the 18th century south of the medieval defensive walls dismantled during the construction of the Jesuit building complex. The outlines of the medieval city walls and gateways are marked with red cobblestones in several streets: Wrocławska, Jaskółcza, Paderewskiego, Szkolna, Wroniecka, Wielka and Wodna. Murna Street runs along the line of the former inner wall. Marcinkowskiego Avenue also hints at the presence of fortifications in times past - it was the first public promenade on the Polish lands, built west of the demolished medieval city walls.
Medieval fortifications limited the growth of the city and were eventually removed in the late 18th century but already in the mid-nineteenth century Poznań was converted into one of the strongest bastions of the Prussian state. A polygonal fort was built and supplemented with a system of outworks several decades later.