Etymology
There are various theories pertaining to the origin of the name Tehran.
The official City of Tehran website says that "Tehran" comes from the Persian words "Tah" meaning "end or bottom" and "Ran" meaning "[mountain] slope"—literally, bottom of the mountain slope. Given Tehran's geographic position at the bottom of the slope of the Alborz Mountains, this appears to be the most plausible explanation of the origin of the name of the city (دامنه ی بین دو کوه).
A second theory holds that the word "Tehran" is derived from Tiran/Tirgan, "The Abode of Tir" (Tir being the Zoroastrian deity equivalent to the Roman deity Mercury). The ancient Parthian town of Tiran was a neighbor to the town of Mehran ("The Abode of Mehr/Mithra", the Zoroastrian sun god). Both of these were mere villages in the suburbs of the great city of Ray/Rhages. Mehran is still extant and forms a residential district inside Greater
Tehran as well as Ray, which forms the southern suburbs of Tehran. The third theory is that Tehran means "a warm place", as opposed to "a cool place" (e.g. Shemiran)—a cooler district in northern Tehran. Some current texts in this regard claim that the word Tehran in Persian means "warm mountain slope" (دامنه گرم).
Modern Tehran
The Azadi Tower is the first landmark visitors come across when arriving from the Mehrabad International Airport. The tower has become an icon for Tehran and a national symbol of Iran.
Tehran suffers from extremely serious traffic congestion and pollution problems. Respiratory ailments such as asthma are very common. Tehran has become so congested over the past decade that the government has considered moving the nation's capital to another city to alleviate these problems and help de-centralize the economy and population. But because Iran's economy and politics are so centralized, millions have little choice but to live and work in Tehran.
The Peacock Throne of the Persian Shahs can be found in Tehran's Golestan Palace. Some of the important museums are National Museum of Iran, Sa'dabad Palaces Complex, Glassware and Ceramics Museum of Iran, The Carpet Museum of Iran, Tehran's Underglass painting Museum, and Niavaran Palace Complex. The Tehran Museum of Contemporary Art features the works of great artists such as Van Gogh, Pablo Picasso and Andy Warhol. Even two paintings by Adolf Hitler are being displayed there. The collection of these paintings was selected by the former Empress Farrah Diba.
The huge Tehran International Fair organises many expositions. Its book expositions are especially popular. Tehran is also the seat of Iran's Parliament (the Majles). And Tehran is also home to the world's fourth tallest free standing structure, the Milad Tower.