The Anzob Tunnel (also called the Iranian Tunnel, having been largely rebuilt with Iranian funding) bores through the Hissar Range north of Dushanbe, replacing the old Anzob Pass that closed each winter under meters of snow. The tunnel is about 5 kilometers long and connects the Dushanbe valley to the Zerafshan valley, cutting the journey to Penjikent and the Fann Mountains from a seasonal mountain pass to a year-round road.
The tunnel is now functional but still not pleasant — it lacks proper ventilation, gets congested with trucks, and the air quality inside can be poor. Keeping windows closed and moving through quickly is advisable. It's a necessary part of the journey north from Dushanbe rather than an attraction in itself, but the approach roads through the mountains on both sides are dramatic.