The 'medinas' or old walled cities of Morocco are a highly varied urban form with a dynamic history stretching over two thousand years. Each medina developed within and as a response to specific regional conditions of geography, climate, politics, and social relations. Most medinas in the Maghreb (Morocco, Algeria, Tunisia) evince a mix of influences from Berber and other nomadic groups; Roman, Arab, and Ottoman incursions; and French colonial occupation. The monochromatic color schemes of some medinas derive from the natural materials once used to build: in the cases shown here, these materials include red clay in Marrakech, rammed earth in Fès, and coral lime whitewash in Essaouira. The morphology of the Medina takes shape around the (usually dead-end) residential street called the 'Derb'. The homes are typically built around a courtyard open to the sky, usually with two to four stories and with few external apertures. Family groups construct their homes adjacent to each other along the Derbs, accreting numerous landscape changes over time. Several Derbs comprise a neighborhood, and each neighborhood has a mosque, communal bread oven, and hammam (baths). Other important structures in the medinas include madrassas (schools), caravanseri (hotel/stable/warehouse for traveling merchants), palaces and their quarters (casbah), public squares and fountains, and the elaborate souks (markets).