The heavily reinforced barracks of the Westerplatte garrison were the backbone of the Polish defence. Here the armoury, dormitories and other important facilities were located. The complex was originally ‘T’ shaped, but after the war several parts of the building were destroyed, for example during the construction of the monument.

The Westerplatte Depot lacked appropriate living quarters for its garrison until the so-called new barracks were constructed in 1934–1935. The three-level building (with a cellar, a high ground floor and a first floor) housed offices, dormitories, an armoury, a gun repair shop, ammunition and storage rooms and other facilities. Its equipment was very modern for its time, with central heating, spacious bathrooms, a sick room and a radio station.

The building was designed in such a way that the ceilings of the two upper floors would absorb the energy of bombs and shells hitting its roof, protecting the crew hidden in the cellar shelter. This system passed the test with flying colours, as the bombs dropped from airplanes did not damage the cellar. A machine-gun room was located in the barracks. Some of its windows were modified for the installation of machine guns. A small machine-gun room with an embrasure survives in the south-west corner of the building.

The south wing of the new barracks housed a sick room and a medicine store. German machine-gun fire from the New Port destroyed its whole equipment in the first minutes of the attack.

Today, the condition of the building is also the result of post-war devastation, which included indoor detonations of unexploded shells and bombs. The northern wing of the barracks was finally demolished in the 1960s to make room for a promenade leading to the mound of the monument to the Defenders of Westerplatte.