The All Hollows level is the reward for finding all the secrets in the game. This level is just for excitement. When you finish this level, you can say that you completely finished the adventure of Lara Croft. When you begin, you slide into a chamber with a large dome in the middle. Make your way up the catwalks to the pillar with the medi pack. From there, jump across to the pillar above the dome. Monkey swing to the middle of the two pillars and be sure to have full health, because the drop you are about to make will almost kill you. Drop down through the cathedral ceiling to the landing below. Be sure to use the medi pack on the landing, then jump across to the purple catwalk and retrieve the flares. Drop down to the walkway above the bookshelf. Climb into the alcove and flick the switch. From there, drop down to the floor below using the small ledge. You may loose some health, but don't worry.
Jump to the central structure. From the ledge, jump, grab the edge, and shimmy to left. Pull the switch that opens a doorway in the corner of the room. Make your way back to ground level and in through the door. Run across the collapsing floor, pull the switch at the end of the hall, and monkey swing back to the main chamber. The switch has closed the trapdoor above the bookshelf. Make your way back up to the walkway and monkey swing to the left and climb the ledge. Climb up past the zip line and retrieve the vault key. Take the ride on the zip line to the platform, but make sure to drop off at the platform or you'll get a great view of the city.
Jump to the pillar, and the bookshelf beside you will open. Drop to the ledge and follow the hallway down. Monkey swing across the flames. You might get a little burnt, so fall into the water below. Swim through the passage and under the piston. When you surface, go straight ahead through the crawlspace. There is a switch that opens a trapdoor in the main chamber. Climb up to the ledge and roll across the trapdoor before it opens under you. Exit into the main chamber and drop down the trapdoor into the water. Surface, open the vault, and jump into the water nearby. Swim through the passage and past the floating mummies to the surface and dispose of the threat. When you investigate the chamber, the level will end.