Riyadh is Saudi Arabia's capital and main financial center, as well as the most populous city in Saudi Arabia. King Khaled International Airport is located about 35 km north of the city. King Fahad and Makkah roads are the main highways. The modern business districts are Olaya and Suleimaniyah with most offices and hotels. Faisalah Tower and Kingdom Centre are major attractions in the modern part of Riyadh. Riyadh Zoo, Masmask Fort, Murabba Palace and the National Museum attract tourists from home and abroad.