Very interesting Portuguese fort at the edge of Rabat medina. As you walk up, someone will invariably tell you the entrance you want to take is closed and that you have to take the other entrance. Ignore these people, they are sending you to their faux guide at the top who wants to follow you throughout the Kasbah and ask for at least 150 dirhams for giving partially accurate information. These are locals, they are not licensed guides. If they have a badge, double check it - it could be an ID card they flash as a guide badge.
Kasbah itself is neat and fun to explore - save an hour or so for this attraction. There is a tea garden with a view of the Bouregreg if you can find it. As you descend the Kasbah you will end up in the garden at the bottom where you'll find a shop if you're looking for trinkets. More