Kashan stands on the edge of Iran's central desert, and its architecture answers that climate with earth-coloured brick, shaded courtyards and buildings that retreat below ground. The Agha Bozorg mosque and theological school takes that principle to its conclusion: the visitor enters at street level and looks down into a sunken courtyard planted with trees, around which the students' cells are arranged, while the prayer hall and its dome rise on the far side between two minarets. The composition is almost entirely symmetrical, worked in unglazed brick with restrained bands of tilework, and depends on the movement of shadow through the day. Filmed in 4K, the programme reads the building as a piece of environmental design as much as a place of worship, and suits strands on Islamic architecture, Persian heritage and desert cities.
