The very long, Jurassic-era Zagros range, down the western border; and the dominant Alborz range, home of Iran's highest mountain, the permanently snowcapped Damavand (5670m/18,600ft), to the north of Tehran. The two great Iranian deserts, the Dasht-é Kavir (more than 200,000 sq km/78,000 sq mi) and the Dasht-é Lut (more than 166,000 sq km/64,740 sq mi), occupy most of the north-east and east of the central plain.

Massive, unrestrained urban and industrial development and the Iran-Iraq War have caused irreparable environmental damage, particularly on the southern slopes of the Alborz range, along the Caspian Sea and around the Persian Gulf. To its credit, the Iranian government has created a few national parks, but the warm glow dissipates once you realize the parks have no fenced areas or rangers. The northern slopes of the Alborz are densely covered with deciduous trees, forming the largest area of vegetation in Iran. There are some lovely pockets of forest around Khalkhal, south of Ardabil, and at Nahar Khoran, just south of Gorgan. Mammals such as the wolf, jackal, wild boar, hyena, black bear and lynx are common in the unexplored depths of the forests of Mazandaran province. In the deserts and mountains you're more likely to come across the more sedate Persian squirrel and mongoose, galloping Persian gazelle, porcupine, badger and endemic Iranian wild ass. Two of the more fascinating creatures are the huge Alborz red sheep, with its black beard and spiraling horns, and the Oreal ram, with a white beard and enormous horns.

Because of its size, variety of topography and altitude, Iran experiences great extremes of climate. Winters (December to February) can be unpleasantly cold in most parts of the country, while in summer (June to August) temperatures as high as 40°C (104°F) are nothing out of the ordinary. Regular rainfall is more or less restricted to the far north and west - generally also the coldest parts of Iran.