As you hike up the steep cobbled road towards the rock, just before the switchbacks and shops leading to the main south face/tourist trail, there is a paved ramp on the right (next to the Hotel Casa Celia) with a parking lot on top. You can park here if you drove a car. In the back of the lot is a dirt road & paved trail on the right (looking towards La Peña) which encircles the entire monolith (it is a busy quad touring trail which has many metal sculptures and signs). There is a manned check-in station here and you need approval to hike the path (may require payment). We went in the early hours of the morning before anyone was there so I cannot confirm this. Hike the path around the Pena until almost directly across from the highest, steepest part of the wall. A climbers trail leads up through the thorny brush and cactus towards the base. Allow 30 minutes.