Bastion I dates back to the so-called “Morando” stage (1596-1600); it was later modernized by Andrea dell’Aqua in 1618-1623
(flank casemates were introduced), by Jan Michał Link in 1685-94 and finally at the time of the Duchy of Warsaw and the Congress Kingdom of Poland (expansion of external fortifications). It was partly blown up in 1866 when the fortress was liquidated. At the beginning of the 20th century a railway track was built through the preserved remains of the bastion. 19th century flank casemates (the right one housing an Oriental martial arts club and the left one housing a seasonal restaurant) have been preserved. It is believed that underground there are remains of defensive walls and embrasures as well as a counterguard with a cofferdam. External part of fortifications was levelled and now they have only been outlined.