St Mark's Unitarian Church, Castle Terrace, Edinburgh

St Mark's Unitarian Church, located on Castle Terrace in Edinburgh, was designed by David Bryce and built between 1834 and 1835. This church showcases a Baroque and Mannerist style, featuring a Jacobean parapet.

The northeast elevation facing Castle Terrace is a two-storey and basement structure with a three-bay Baroque design. It is constructed of polished sandstone ashlar, with the ground floor channelled. The bays are separated by channelled pilaster strips at the ground level, with Doric pilasters flanking the entrance. The first floor features Corinthian pilasters, with paired pilasters flanking a larger central window. Access is provided by stone steps leading to a panelled and decoratively carved two-leaf studded timber door set in a round-arched opening. The doorpiece is adorned with Doric columns and an open-topped segmental pediment that encloses a heraldic cartouche. The flanking bays contain blocked windows with moulded surrounds. The first floor has three tall round-headed aproned windows with lattice leaded glazing, each topped with scrolled open-topped segmental pediments that also contain cartouches. A deep bracketed cornice runs along the top, and the roof features a pierced strapwork parapet with an inscribed centre panel, a scrolled open-topped segmental pediment with a cartouche and finials, and urns at the outer corners.

Inside, the church features slim cast-iron Doric columns and decorative consoles that support a horseshoe gallery with original pews. Fluted Corinthian columns hold up an arched, compartmented ceiling. Round-arched two-light windows with lozenge-pattern leaded glass flank a white painted octagonal sounding board topped with a finialled ogee canopy. The organ is located at the rear of the gallery within a carved wooden case.

The entrance is flanked by spear-headed cast-iron railings and decorative cast-iron lamp standards.