The beauty of bare places
The rocky Grau dels Tres Esglaons route is very well equipped with metal rungs, but can be rather exposed for people with vertigo. In this case, or if you have children with you, it is better to go up and down by the Grau del Tomaset, also known as the Grau de Montsant, the path traditionally used by the people of Cornudella to get up to the Serra Major, the main ridge of the Montsant massif. You should fill your water bottles at the chapel.
The suggested route begins at the chapel of Sant Joan del Codolar. You can get there by car from Cornudella, along the old cart track that starts out beside the cemetery.
Go round to the right of the building, passing above the apse of the chapel. This is where the well-trodden path of the  Grau dels Tres Esglaons sets out, marked with piles of stones. This is not so much a path as an adventurous route to climb to the top. It goes straight up a gully, climbing over three rocky outcrops with the aid of metal rungs rather like on a via ferrata. After climbing the last of these outcrops, head right along a level path to join the path up to the Roca Corbatera.  You can go back the same way or go a little further along the top of the Serra Major, the main ridge, as far as the dip that leads to the entrance to the Grau de Sant Joan route.  From here take a path that runs beneath the imposing walls of the Roca del Migdia (the Midday Rock) to get to the flat area around the cave known as La Cova del Moloner.  The well-known cave of the Cova Santa is here. The first chamber is not hard to get into, but care should always be taken. Nearby are the red and white markings of the GR 174-1 long-distance path, which goes down by the Grau del Tomaset route, or Camí de Montsant. This was an important mule track, even though some sections are now in a poor state.  Near the chapel of Sant Joan, beside the signpost, is the start of the path (marked as GR 174) to get back to your starting point.