Beyond the ramparts at Bab Agnaou lies this highly underrated ruined palace. It’s well worth a visit being almost deserted (a refreshing change from the heaving crowds at the Saadian necropolis and Palais de la Bahia) and extremely atmospheric (though the peace can be broken somewhat by the erection of scaffolding in the centre--concerts are held here from time to time; the acoustics are good and it must make for a spooky location).
Judging by the impressive spread of the ruins, the palace seems to have extended across the whole area east of the Kasbah mosque (which you can see in the distance). It was built by Ahmed Al-Mansour between 1578 and 1602 and called at the time "the Incomparable" (if it was anything like the palaces which remain intact, you have to wonder whether apparent hyperbole wasn't likely in fact to have been a fair description--apparently, marble was imported from Italy and precious metals and stones used liberally). Unfortunately in 1696, Moulay Ismail was building his new city at Meknes in the north and ransacked the palace for materials so little is left. At the very rear of the ruins, you can just about make out some fresco remaining in place but it's a far cry from the splendour the palace must have enjoyed in its heyday.
You can scramble up and down over various areas, including climbing up some steps to the top of a two-storey building to the left as you enter (the Koubba al-Khamsinyya) to reach a terrace which presumably used to have fountains and tiled floors and columns (some of the columns remain). From here, you also have a great view across the sunken orange groves to a small temple building and the Kasbah mosque in the distance (see below).
On the far left hand side, beyond the orange groves, you can climb around the ruins of the palace kitchens and offices, through underground passages (bring a torch and mind your footing). It takes a little imagination (maybe that's why it's often ignored), but it's a peaceful and relaxing spot for a hour spent meandering and exploring.
It also seems a popular home to nesting storks, whose impressive constructions lean precariously from the narrow walls and chimney-tops (see photo below)-- the storks also form mighty swirling flocks at sunset.
Open 9am-5pm; entrance 10dh.