Badab-e Surt is a hillside of travertine terraces in the Alborz mountains of northern Iran, in Mazandaran province, where two mineral springs have built a staircase of pools stained rust-red and ochre stepping down the slope, and the springs are still building it. The terraces are the same kind as Pamukkale's, limestone laid down by spring water as it flows and cools, but where Pamukkale's are pure white these blaze orange and red, because the water here carries iron, and each pool is rimmed by a fretted crust of carbonate in rust and cream, thin ledges and frozen ripples that you crouch to look at. The two springs are different: one is salty and one is sour, and the salty one runs so heavily mineralised that people have long soaked in it as a remedy for rheumatism and skin conditions rather than as a sight. The terraces sit at 1,840 metres among bare hills and cypress, reached by a rough road from the village of Orost, and they were almost unknown outside Iran until a decade ago.
The way to see them is twice. From the top edge of the slope the terraces line up as one continuous flight of pools spilling into each other down the hill, red water in orange bowls with the hills and sky reflected; from below, at water level, each pool is a mirror rimmed with crust, and the flow between them is a sheet a finger deep. The hour is first light, before the sun clears the ridge, when the road is empty and the air is coldest, and the colour comes up as the light hits the wet stone; at sunset the red deepens again. Walking on the terraces is no longer allowed, since boots break the crust that took centuries to form, and a boardwalk keeps visitors beside them. The pools are warm from the springs and steam on cold mornings. Badab-e Surt is Iran's red Pamukkale, and the springs are still laying the steps.