Hassan Tower or Tour Hassan (Arabic: صومعة حسان) is the minaret of an incomplete mosque in Rabat, Morocco. Begun in 1195, the tower was intended to be the largest minaret in the world along with the mosque, also intended to be the world's largest. In 1199, Sultan Yacoub al-Mansour died and construction on the mosque stopped. The tower reached 44 m (140 ft), about half of its intended 86 m (260 ft) height. The rest of the mosque was also left incomplete, with only the beginnings of several walls and 200 columns being constructed. The tower, made of red sandstone, along with the remains of the mosque and the modern Mausoleum of Mohammed V, forms an important historical and tourist complex in Rabat.
Instead of stairs, the tower is ascended by ramps. The minaret's ramps would have allowed the muezzin to ride a horse to the top of the tower to issue the call to prayer.