The Perseus Riddle is a puzzle found in the Lara Croft Tomb Raider: Anniversary level Greece - St. Francis Folly. Throughout the first part of the level Lara encounters murals depicting Perseus with a sword and the head of Medusa.
As Lara so nicely states in her thoughts recorded in the Journal, "the murals around the room aren't just for decoration", they serve a higher purpose.
On the main balcony Lara can spot a metal globe behind a grate, on the wall behind she finds a large mural with ten glowing stars and a Pressure Plate in front. By stepping onto the pressure plate the spots turn to Shootable Buttons. By shooting certain buttons Lara can enter different combinations. She can always reset the combinations entered by stepping on the pressure plate again.
The Three Combinations
Overall there are three combinations to be entered.
The first one opens the gate just around the corner from the main mural. The image shows the stars on the tip of Perseus blade (1) and the eye of Medusa (2) glowing. Lara needs to return to the Shooting Wall, reset it and enter the combination to open the gate. This gate leads to a mural with the second combination.
This combination, which shows both of Perseus' feet (1+2), his sword-wielding hand (3) and the one at his lower (4) back ablaze; when entered, opens the gate to the metal globe.
The third combination, which can be found in the entrance room to the stairs leading downwards at the end of the first part of the St. Francis level, is optional for finishing the game. It will open the portal to an Artefact. The combination is both of Perseus' feet (1+2), the eye of Medusa (3), the tip of the blade (4), the sword-wielding hand (5), the lower back (6) and the knee (7).
Lara on the Pressure Plate