The Portuguese circuit of walls is Azemmour's most impressive sight. Built and reinforced during the 28 years of Portuguese occupation (1513–1541), they follow the curve of the Oum er-Rbia river and are best appreciated from the opposite bank, where the full scale of the fortifications becomes clear — towers, crenellations, and whitewashed medina houses rising directly from the water.
The ramparts are walkable from within the medina, and some sections allow access to the top, with views over the river mouth and the Atlantic beyond. In recent years the old city walls have attracted a community of street artists, who have painted murals on the outer faces — an unusual and not unpleasant combination of medieval military architecture and contemporary art.