St Andrew's Church, Olrig Street, Thurso

St Andrew's Church on Olrig Street in Thurso is a large Gothic church designed by architect J Russell Mackenzie from Aberdeen in 1870. The church is oriented southwest to northeast and features coursed rubble with tooled ashlar dressings. Its gabled front facing the street is highlighted by a large projecting canted porch that rises to full height, showcasing large geometric traceried windows in the center and side bays, flanked by buttresses.

The entrance includes a recessed center gabled porch with nook shafts and a trumeau. To the left of the entrance is a polygonal gallery staircase bay topped with a pyramidal slate roof, while to the right, a square tower rises through four stages. The upper stage of the tower has louvred vents and truncated angle pinnacles, supporting a lucarned and facetted spire faced with ashlar, which features clock faces under stepped gables at its base.

The church's flanks are crowstepped gables with tripartite windows on the ground floor and geometric traceried windows above. The northeast apse is canted and has single-storey extensions that mask its base. The roof is covered with slate.

Inside, the church has a galleried interior with an ornate bombe cast-iron gallery front, supported by cast-iron columns with fluted square capitals. There is also a memorial in the porch dedicated to Sir George Sinclair of Ulbster, who died in 1868.