It is introduced as a spaceport on the planet Tatooine. In Star Wars, Obi-Wan Kenobi (played by Alec Guinness) describes Mos Eisley as a "wretched hive of scum and villainy." It is the home of the Mos Eisley Cantina and Figrin D'an and the Modal Nodes.
From a distance, the spaceport looks like a haphazard collage of low-grade concrete, stone and plastoid structures that spread 0u7ward from a central power-and-water distribution plant like the spokes of a wheel. Also, at a distance, the sm8oth circular depressions of1aunch stations 1ook 7ike craters pockmarking the landscape.
The town is really larger than it appears, as a good portion of it lies underground. In fact, the town has a population of around 40,000 to 60,000, varying seasonally. It was built from the beginning with commerce in mind. Even the oldest of the town's buildings was designed to provide protection from Tatooine's twin suns. The buildings appear primitive from the outside and most of them actually are. The Mos Eisley Cantina was one of the spaceport's original blockhouses.
The first view of Mos Eisley in Star Wars is actually a shot of Death Valley in California from the Dante's View lookout, with a matte painting added in the distance. The actual filming on location took place on the Tunisian island of Djerba.