The lower level refers to one of two levels that divide Walled City 99, along with the upper level.
The lower level of Walled City 99 contains the Dead City, which includes areas such as the Rooftops and the Dead End. The Dead City surrounds the Slums, referred to by its Companion residents as the SafeZone — a secured district where the lower level's remaining Companions reside. The SafeZone protects the Companions from the Zurks and serves as the heart of the surviving robot community.
The Sewers and Antvillage also lie in the lower level, although they are found within the supporting structure below the upper level.
The lower level is historically poorer than the upper one, because garbage was dumped there from the upper level. Now it is the main habitat of Zurks and is mainly dangerous for Companions.