Anyone who has ever been to the Marrakech Medina will know that street signs by and large don't exist and that many of the places you want to get to are down a range of alleyways.
As a result, mapping out the Medina is a huge undertaking, but Rough Guides have done it, and done it successfully. By listing each of the hundreds of restaurants and Riads on the Medina streets, you are effectively given a sign-post of where you need to go.
By using the map we never got lost once and even managed to get to Richard and Sophie Neat's destination restaurant / Riad, "Casa Lalla" under our own steam, where we had previously been warned we would need to pay someone to take us there.
Highly recommended and will definitely be using it on my next trip over there.