If this cluster of beguiling streets seems familiar, it may be because you've seen the film Inception (2010); the chase scene featuring Leo DiCaprio was filmed here. The most characterful part of Mombasa is great for a wander, its houses characteristic of 19th-century Indian-style Zanzibari architecture, with ornately carved doors and window frames and fretwork balconies. Some parts of the Old Town can be a little sketchy, even during the day, such as the Leven Steps and Vasco da Gama's Well, so going around with a reliable local guide (such as Suleiman Sabdallah) is not a bad idea.
In this city of almost one million inhabitants, 70% of whom are Muslim, there are a lot of mosques. Non-Muslims are usually not allowed to enter them, although you can have a look from the outside. There are also two large Christian churches that are worth seeing. Wander some more and you'll pass various Hindu, Jain, Sikh and Hare Krishnan temples.