Saffron is your first clue for today's Geo Quiz. We're looking for the main city in a saffrongrowing region in Iran.

The city is nestled between two mountain ranges in Iran's northeastern corner. It's also near the border with Turkmenistan.

The city's name means, "The Place of Martyrdom." Its home to one of the holiest shrines in Shia Islam.

It's also Iran's second-largest city after Tehran -- and a good place to buy saffron.

Saffron threads

But first you have to name Iran's second-largest city...