The Big Walk map and compass location is inside the Map Room opened through Red Tower progression. After preparing the Red Tower key, follow the red-area route to the blue tunnel building with a red staircase; the portable map and compass sit on a table to the right inside.
Unlock the Map Room
Complete enough puzzles to earn the control-panel key at the Red Tower, then use the required key cutters to prepare it. From the tower route, head toward the large red circular platform and follow the cutter arrows to the nearby blue tunnel structure.
Do not confuse this building with the Blue Tower farther into the mountains. The Map Room is in the red area and has a red staircase leading to its entrance.
Pick up the portable tools
Inside the room is a three-dimensional terrain model that develops as the group explores. The table on the right from the entrance holds the portable map, compass, and laser pointers.
The map and compass are separate carryable objects. Distribute them between players or store them in available carrying equipment so a single lost walker does not remove every navigation reference from the group.
Read the coordinate grid
Big Walk uses four-digit coordinate values to identify a grid square and then add precision within that square. The map's numbered lines identify the main longitude and latitude, while the final two digits describe how far across or down the target sits.
The 4166 and 1899 puzzle demonstrates the system directly: use 41 and 18 to choose the square, then 66 and 99 to narrow the position. A GPS device elsewhere in the world can provide a live coordinate readout, but the portable map and compass are sufficient for the published solution.