Turkmenistan's most remarkable sites are outside Ashgabat, and a stay in the capital is best combined with excursions to at least one or two of them.
Darvaza Gas Crater (about 260km north) is the most extraordinary sight in the country — a natural gas field that was set alight by Soviet engineers in 1971 to burn off the gas, and has been burning ever since. The crater, roughly 70 metres wide, glows an eerie orange at night visible for miles across the Karakum desert. Reaching it requires a long drive across the desert, typically combined with camping overnight. Most visitors arrive at dusk and camp beside the crater.
Ancient Merv (about 380km east, near Mary) is a UNESCO World Heritage Site and one of the great cities of the Silk Road — at its peak in the 12th century, it was possibly the largest city in the world. The site preserves the ruins of multiple successive cities built on top of each other across 4,000 years, including impressive mausoleums, a Sultan Sanjar's mausoleum, and vast mudbrick ramparts. A full day is needed. Fly to Mary or drive with a guide.
Nisa (15km west of Ashgabat) is an ancient Parthian capital and UNESCO World Heritage Site — the remains of two fortified cities with round towers and fragments of ivory rhytons (drinking vessels). A manageable half-day excursion from the capital.