The St. John's Church in the Hamina city centre was built in 1841-1843. It was designed by famous architect Carl Ludvig Engel and represents the Neoclassicism style with strong influence of Greece temples.
Before the present church there was a church of Ulrika Eleanora (built in 1732, destroyed by fire in 1742) and the commandant’s house. The residence of the fortress commander was the place where the Russian negotiators lived and signed the Treaty of Hamina (after the Finnish War in 1809).
The Broch of Gurness is an Iron Age broch village. Settlement here began sometime between 500 and 200 BC. At the centre of the settlement is a stone tower or broch, which once probably reached a height of around 10 metres. Its interior is divided into sections by upright slabs. The tower features two skins of drystone walls, with stone-floored galleries in between. These are accessed by steps. Stone ledges suggest that there was once an upper storey with a timber floor. The roof would have been thatched, surrounded by a wall walk linked by stairs to the ground floor. The broch features two hearths and a subterranean stone cistern with steps leading down into it. It is thought to have some religious significance, relating to an Iron Age cult of the underground.
The remains of the central tower are up to 3.6 metres high, and the stone walls are up to 4.1 metres thick.