When you get to Marciana Alta, you'll see the first junction with a sign saying Marina di Campo to the right, then Chiessi, Pomonte, Sant'Andrea, and so on.
Take the turning on the left where there's a yellow sign saying Archeological Museum.
You then get to another junction, and turn left again, following the signs for the Archeological Museum and the Pisan Fortress.
Park your car and continue on foot. After about 250 metres, you'll see a grit open space with a huge pine tree in the centre.
The path represents the Stations of the Cross. There are 12 chapels on the left side. The path with the chapels starts from the town, so if you take this short cut there are less chapels.
Once you get to the Madonna del Monte Church get your water supply from the spring in the amphitheatre behind the steeple, at the entrance to the church, where you'll see a sign saying num. 3 of the CAI for Chiessi and Pomonte; go straight on towards the rocks (see photo 2).
It takes about 30 minutes to get there.