Ancient Merv

Merv, Turkmenistan — once one of the largest cities on Earth and a major Silk Road hub, now a vast UNESCO-listed field of crumbling mudbrick mausoleums and fortress walls in the desert.

The Great Kyz Kala fortress and the Mausoleum of Sultan Sanjar are the most intact structures across the sprawling, mostly unexcavated site — hire a guide in nearby Mary, as there's little signage and the ruins are spread over several kilometers. Merv was largely destroyed by the Mongols in 1221 and never fully recovered, leaving its scale essentially frozen in ruin.