From The TimeSplitters Wiki

Tomb
Size	Small
Location	Deep inside an Egyptian Tomb
Climate	Desert outside
Unlockable	Unlocked by Default
Recommended Bots	N/A
Recommended Weapons	N/A

The last section of Tomb (Hard mode), features a surrounding platform and rooms around the perimeters. This level is only featured in Timeplitters 1, but the Egyptian tileset in TSFP is based on many of the pieces in this level.

Although on the Arcade map the door entering the last room has been removed.