The buildings handed over to the Cadet School by the Russian Engineering Department on June 20, 1819 were located inside the fortress in the north-eastern part of Hamina. In the east, the area was bounded by the Viborg Gate and on the other side by the rectory of the Orthodox congregation. The St Peter’s and Paul’s Church, demolished by the Orthodox congregation in 1830, was in the middle of the main parade field. The original Cadet School's main building and administration building from 1807-1809 were on the northern and southern edge of the field. Originally built as barracks, these buildings had been renovated in a neoclassical style designed by C.L.Engel, director of the intendant's office. The renovated buildings were elegant with Ionic columns in the central part of the facade. The new main building of the Imperial Finnish Cadet School, designed by Jacob Ahrenberg, was completed in 1898 to replace the previous cadet accommodation building. Since 1920, it has been used by the Reserve Officer School. The Manege of the Cadet School from 1832, designed by Carl Ludvig Engel, and the banquet facilities built in the 1960s are connected to the main building through the hinged part. The old administration building was replaced by a new administration building in 1875 on the southern edge of the field along the current street, Kadettikoulunkatu. The main building of the Cadet School is located next to the chain of 18th-century fortifications surrounding the city centre. After the Cadet School and before the Reserve Officer School, the building also housed units of the 6th Finnish Sniper Regiment of the Russian Army. During the summer and autumn of 1918, Finns were trained in the building at the German-led Hamina Combat School and at the Fahnenjunker officer course, which prepares for cadet training.