September to October is Turkmenistan’s mild autumn and the best time to visit. Temperatures in Ashgabat are between 11 and 24 ºF (52-74 ºF) with hardly any rain. Many travelers use this season to visit Merv, a small city that was a leading metropolis of the Silk Road some 2,500 years ago. Today it ruins are a Unesco world heritage site, consisting of five walled cities from different periods. Another popular site is one of the world’s more unusual natural attractions, the Darvaza gas crater in the bleak Karakam desert. Often referred to as the‘the door to hell, ‘the origin of this 30m-deep pit of flaming methane is shrouded in mystery, but it’s been burning for 40 years. Camp here to watch its bizarre glow at night, when passing birds and insects are attracted by its searing beam.