Ruins of one of the great Silk Road cities
Merv was a major city of the Silk Road for over two thousand years, and in the 12th century it was among the largest cities in the world before the Mongols sacked it in 1221. Its remains form a series of walled cities of different eras spread across the plain, from the Achaemenid Erk Kala to Sultan Kala of the Seljuks. The Mausoleum of Sultan Sanjar, with its great dome, is the finest surviving building, and the ribbed mud-brick walls of the Kyz Kala fortresses are strangely beautiful. Merv is a UNESCO World Heritage Site.