Yazd, a city right in the middle of two Iran's harshest deserts, the Dasht-e Kavir and the Kavir-e Lut. This isolation has led to it avoiding many of the wars and battles which destroyed many of Iran's other cities and has left a beautifully preserved ancient city. Genghis Khan never made it here, but Marco Polo did and he wrote extensively about it. I found it a great place to visit, ideal for walking and exploring, and it is the home of the best Baklava in Iran.