Monuments

Ostrołęcka Gate is situated in the eastern part of the fortress on the Narew River. It is a three-level defence gate built in 1836 with an entrance centrally located on the ground. During the World War I or even earlier there was another entrance made in this gate. Later a narrow gauge railway was conducted through this entrance. The railway had its route along the River Narew.
The exterior of the first floor was supplied with pairs of ranges. Inside the "Ostrołęcka" Gate has some features of classical architecture.