One of the largest covered bazaars in the world and a UNESCO World Heritage Site, the Grand Bazaar has been the commercial engine of Tabriz for at least 600 years. The present structure dates largely from the 15th century, though the complex is certainly older — buildings like the Jami Mosque and Sadeqiyeh School suggest an origin well before that.
The bazaar is a city within a city: dozens of interconnected halls, caravanserais, mosques, and schools, each section historically dedicated to a different trade. It is already much diminished in variety compared to its Silk Road heyday, but the architecture alone justifies the visit. Getting pleasantly lost in the vaulted corridors is part of the experience.