Zoroastrianism may only have a modest two-million-strong following worldwide nowadays, but before Islam, it was the state religion in Iran. Its beliefs are rooted in the dichotomy between good and evil, much like Christianity and Judaism, both of which it influenced. ‘The Everlasting Flame’ maps out the history of Zoroastrianism via a selection of texts, paintings, artefacts and textiles. Among the exhibits are a walk-in fire temple and a 10-metre glass etching based on the cast of the western staircase from the palace of Darius at Persepolis in the British Museum.