From the Introduction:
The Lost City is the most prized adventure ground for the player characters. The city usually hides many secrets, keep great treasures and, of course, features great dangers. The Lost City can be placed beneath the sands of a desert, in a vast underground cavern or in the depth of the ocean. The Lost City is divided in two zones: the normal city and the kings dwelling. Obviously, this city should have been ruled by a powerful god-king or by a mighty clergy since the main area is completely devoted to temples and crypts. A stone wall encircles the kings dwelling and most of the temples inside it lie beneath the surface ground. A large pyramid, keeping the crypt of a long forgotten god-king, overlooks the entire complex. The maps presented here cover most of the kings dwelling, consult the suggested key at the end of the product to find out how the maps join each other.
Some hints to use the Lost City follows:
The City lies among the sands of a desert. Nobody is able to find it without a magical artifact. Looking through the artifact the city appears, otherwise is invisible. The PCs soon will discover that the magical artifact allows them to see the city dangerous inhabitants...
Trying to awaken an ancient evil buried in the pyramid crypt.
The PCs find a magical gate that transports them in an underwater lost city, the gate closes behind the PCs. The PCs explore the underwater city and meet treasures and dangers.
A cult of serpent-men occupies a ruined city in the desert. They seek an ancient artifact buried in the city that would allow them to spread their cult all over the humankind. The PCs must infiltrate within the cult and search in the kings dwelling in order to find the artifact before the evil cult.