Climb the steps behind the Drölma Lhakhang, passing a rocky fissure jammed full of tsha tsha (stupa-shaped clay offerings) and cracks stuffed with little bags of wishes and human hair. Eventually you’ll come to the walls of a large white monastery, inside which is this small cave. Take off your shoes and duck between the monastery buildings to reach the soot-darkened cavern, which is illuminated by butter lamps and a row of coloured lights.