Climb onto the single container just to the left (when facing the door with the lion). Walk to the edge closest to the two stacked crates and jump to grab the edge (as indicated by the arrow in the screenshot above). Pull up.
Turn left and set Lara up for a running jump. When the magnet brings the container down to a position just a little higher than the one Lara is standing on, take that running jump to grab the edge of the suspended container (indicated by the arrow in the second screenshot). Pull up. Then ride the container to the other side of the room.
[Return to the Strahov Fortress walkthrough]