Tehran is the capital of Iran and Tehran Province since 1778. With a population of around 8.3 million and surpassing 14 million in the wider metropolitan area, Tehran is Iran's largest city and urban area, and the largest city in Western Asia. In the 20th and 21st centuries, Tehran has been the subject of mass migration of people from all around Iran. The city is home to many historic mosques, churches, synagogues and Zoroastrian fire temples. However, modern structures, notably Azadi (Liberty) Tower and the Milad Tower, have come to symbolise the city. Tehran is ranked 29th in the world by the population of its metropolitan area. Throughout Iran's history, the capital has been moved many times, and Tehran is the 32nd national capital of Iran although it has been Iran's capital for 240 years. Although a variety of unofficial languages are spoken, roughly 99% of the population understand and speak Persian. The majority of people in Tehran identify themselves as Persians. In pre-Islamic and early Islamic times, Tehran was an unimportant village and part of the area of present-day Tehran was occupied by Rey (which in the Avesta occurs in the form of Rhaga), now a part of the city of Tehran, which took over its role after the destruction of Rey by the Mongols in the early 13th century.An important historical city in the area of modern-day Tehran, now absorbed by it, is known as Rey, which is etymologically connected to the Old Persian and Avestan Rhages. The city was a major area of the Iranian speaking Medes and Achaemenids. Tehran became the capital of Iran in 1778. In the Zoroastrian Avesta, Videvdad, i, 15, Ragha is mentioned as the twelfth sacred place created by Ahura-Mazda. In the Old Persian inscriptions, Ragha appears as a province. From Ragha, Darius the Great sent reinforcements to his father Hystaspes (Vishtaspa), who was putting down the rebellion in Parthia .