The mausoleum, or most commonly known as Le Tombeau de la Chrétienne is the tomb where the daughter of Cleopatra, Cleopatra Selene II, and her husband, Kind Berber Juba II, are burried.
The mausoleum, which is shaped in the form of a pyramid, has only one real door to enter.
Unfortunetly it is now on the list of the endengered UNESCO world heritage sites due to poor maintenance.
Access is not easy, as it is off the highway, but any local guide would be able to organise a trip from Algiers. If you are into culture, the visit can be combined with a visit to the Roman City of Tipaza nearby.