The Northeast's primary attraction is Mashhad’s extraordinarily grand Haram-e Razavi complex – the shrine of Imam Reza – which attracts pilgrims in their millions. The main highway to Mashhad from Tehran parallels the classic silk route via a series of former caravanserai villages and towns edging round the vast desert emptiness of the Dasht-e Kavir. An alternative route crosses the Alborz Mountains, descends to the highly developed Caspian coast then passes through Turkmensahra (an area that's culturally Turkmen), skirting the ancient Hyrcanian oak forests of the Golestan (Paradise) National Park, mountain home to a small population of leopards.
There's much to discover here – and you'll need to come this way if travelling overland to Turkmenistan – but foreign tourists remain extremely rare throughout the region. Cities like Semnan, Shahrud, Gorgan and Mashhad are vibrant and increasingly modern, but don't expect to find many English speakers or even any Latin script on most signs.