La Roche Percee(Ain county). GPS 45°51.855'OO5°44.741' Directions : From the center of the village of Culoz (crossroad), drive road D904 (north) for 2.3km to "Beon" and turn right at sign "Les Guichards". Drive 500 meters this road and turn right (second road). Drive up 200 meters and park at the old wash-house. From there, hike north the paved road and contine on the 4wd road 15 minutes to the curve. At the hiking sign "Romagneux par la Roche Percee, take the strenous trail (north) up to the arch( 20 minutes). The trail cross the arch. The arch is located on the Grand Colombier mountain and has a span of 14.5 meters. Also visit Groin Canyon (7km distant), Spider Web Bridge & Cerveyrieu waterfall (9km distant) and Trou de la Marmite (28km distant).