Imagine this. You're cruising along through the barren, rocky desert in the back of a dusty Mercedes taxi...no building, no trees, just nothing. After about 10 minutes, you follow the curve around a barren hillside and come across a verdant valley; a true oasis of trickling creeks and date palms and at the center of it all is the spectacular Kasbah Aït Ben Haddou like something out of a fairy tale. It's simply indescribable!
The Kasbah is more or less abandoned excepts for store fronts and a few cafés. You'll arrive in the town itself, but you need to cross the river to get to the Kasbah itself. First, follow the roads in town down to the river to get some amazing views of the Kashab head on, then head towards the concrete bridge (you'll see it) to cross into the Kasbah itself. There's no entry fee and you can explore the Kasbah at your leisure.
I'd suggest winding your way to the very top via the signs that point you along the way. Make your way to the fortified granary atop everything and you'll be rewarded with some simply stunning views of the valley. Then, head down towards the river where the big towers are and you can pay the "owner" (typically a friendly old Moroccan woman who might invite you to have a tea) 10 Dirhams (around $1.20) to enter the buildings. This is the best part, in my opinion. You climb up the winding stairs and explore the various floors, patios, and courtyards with no other tourists around. You feel like Indiana Jones. When you reach the top, you really feel like you're in a different world.
All in all Aït Ben Haddou was probably one of the best things we did in Morocco. It's probably worth the journey in and of itself. For me, it's one of the wonder of the world!