Until the 16th century, Riyadh (or Ar-Riyadh) formerly known as Hajr. Riyadh is a city with hot desert climate. Being a desert city, Riyadh today is one of the fastest growing cities in the world. Riyadh has developed into a global city and become a focal point for both travel and trade. It is now one of the richest cities in the Middle East and the 80th richest city in the world.