Tabriz has the largest covered bazaar in the world: 5.5 km, covering 27 hectares, or 1 million sq metres. It was rehabilitated using traditional building techniques, as recognised when it won the 2013 Aga Khan award for architecture, following on its inclusion as a UNESCO world heritage site.
The Guardian has just done a photo gallery focusing on the bazaar, but I think the Aga Khan video below is much more interesting.
Click here for 2.47 fascinating minutes