Tomb Raider I-III Remastered Starring Lara Croft

An easy place to obtain this is to simply jump off the platform at the very start of The Great Pyramid level.

An easy place to obtain this is to simply jump off the platform at the very start of The Great Pyramid level.

Tomb Raider I - Atlantis (Level 14)

At the very end of the level, avoid pickup up the Scion and you can obtain two achievements. Make a save then jump off the ledge behind the dais into the lava to activate two+ screams on your way down. Reload and this time jump onto the large square platform (make sure you have enough health), then turn 180 and jump into the hallway behind the now open door on the left for Secret Door.



Video:

Done in TR1 - Atlantis

I suggest here because you can get both Shelley's Encore and Secret Door achievements from here.

Make a save at the very final room of Atlantis with the Scion holder in it (pressing the action button on this finishes the level, don't do this yet).

To get Shelley's Encore just run off the edge to the long drop down to the lava.

To get Secret Door, do a running jump to the final boss platform. Look to the right and you'll see a red square in the wall (in modern graphics) - head to that square and a "secret door" will open allowing you to loop back to the drawbridge room prior.

The achievement will unlock once you jump through the secret door.

Image below in case they fix the lighting of the door in a future patch, or if you prefer Classic graphics where the door is less obvious.