From The TimeSplitters Wiki

For the Story level, see: Mansion (Story)

Mansion
Size	Large
Location	Old Mansion
Climate	Dusk/Night/Abstract
Unlockable	Completeing Story mode up to Planet X
Recommended Bots	N/A
Recommended Weapons	N/A

The Mansion map with all of the doors open. Although it has a fair amount of corridors, it isn't hard to get lost.