Exploring the ruins of a once-glorious Buddhist monastery at Sigiriya, most people stick to the main path, whether from lack of energy or led by a guide unwilling or unable to manage anything more than the bare minimum tour. With too much time on my hands, I strolled slowly around mostly unmarked ruins, attaching no meaning to the millennia-old structures but admiring the water system engineering. Rain collection systems, covered water channels, pipes hewn from granite, reservoirs built from bricks or carved out of solid bedrock, overflow outlets to other reservoirs, deep access manholes to unblock channels – the people who built the massive monastic complex at Sigiriya were incredibly clever.

As it turned out, I was not the sole person admiring the waterworks that day; I found this metre-long lizard monitoring a covered channel through which water could flow from one tank to a lower one: