Tus (also spelled Tous) is an ancient city near Mashhad in northeastern Iran, easily visited as a day trip from that city — the drive is about 30km and takes around 40 minutes. The main reason to come is the tomb of Ferdowsi, author of the Shahnameh (Book of Kings) — the national epic of the Persian-speaking world, written around 1000 AD. The mausoleum, rebuilt in the 1930s in a style evoking ancient Persian architecture, sits in a garden and is a place of genuine reverence for Iranians. It is open daily from early morning.
Tus was once a major city — it was the birthplace of both Ferdowsi and the Sufi philosopher Al-Ghazali — but was destroyed by the Mongols in the 13th century and never recovered. Little remains of the old city beyond some walls, a citadel mound, and the Haruniyeh dome, an Ilkhanid-era structure sometimes identified as Ghazali's tomb. Most visitors come with a driver from Mashhad; the two sites can be seen in two to three hours.