Stand on the Hassan plateau above the Bou Regreg river and you are looking at one of the most ambitious — and most interrupted — building projects of medieval Morocco. Almohad sultan Yacoub al-Mansour began Hassan Tower in 1195, fresh from his victory at Alarcos, intending the minaret to crown the largest mosque in the western Islamic world. The tower was planned to reach 86 metres; when al-Mansour died four years later, construction stopped at 44 metres of pink sandstone and never resumed.

The mosque itself never rose above its foundations. What survives is a 2.5-hectare plateau studded with around 200 column stumps, set out in ordered rows that mark where the prayer hall would have stood. Facing the tower across the esplanade is the Mausoleum of Mohammed V, a 20th-century building completed in 1971 under King Hassan II — a green-tiled pyramid roof over a marble chamber housing the tomb of the modern founder of independent Morocco, with the tombs of his sons Hassan II and Prince Moulay Abdallah added later. Royal Guards in red capes flank the four entrances.

Entry is free to both the esplanade and the mausoleum. The mausoleum keeps a respectful silence rather than a strict dress code — shorts and sleeveless tops are discouraged, and a light scarf to cover the shoulders is a reasonable courtesy. The whole site forms part of the UNESCO-inscribed historic ensemble of Rabat (2012), alongside Chellah and the Kasbah of the Udayas.