Park next to the water tower. Walk directly from there into the woods, following the path straight until you reach the viaduct. Viaduct Boulder: Scrambling down the steep bank to the right will get you to the viaduct boulder though a more amenable (but longer) approach is to head towards the Hueco Boulder and follow tracks down to the main path that runs under the viaduct. Follow the main track back to the viaduct where you'll find the boulder. Hueco Boulder: From the viaduct, continue straight on into the woods (perpendicular to the viaduct). After 400 m or so you'll see the boulder down and right of the trail. Graffiti Wall: Same as for the Hueco Boulder but after 200 m or so the wall is visible up and left of the track.