Before you see the town, you have to earn your way in: crossing the Ogarrio Tunnel, 2.3 kilometers bored through solid rock that emerges directly in Real de Catorce. There is no vehicle alternative: anyone arriving by car, bus or van passes through here.
A tunnel born of mining
The tunnel is heir to the real's mining heyday: it was excavated as an engineering work to connect the town with the outside world across the mountains. San Luis Potosí Tourism describes it as an "extraordinary feat of engineering," and local press from Matehuala dates its construction to the early 20th century. Crossing it today is still an experience: the desert light fades, the air cools, and after a few minutes the rock opens onto the town.
How to cross it
The stretch before it is already mountain road: tight curves from the Cedral turnoff. It's best to arrive in daylight the first time. Inside the tunnel, drive slowly with your lights on. When you exit, park the car — the rest of the day is on foot, because the cobblestone streets forgive nothing else.
On the other side
The Main Square is a few minutes' walk away, with the Parish of the Immaculate Conception at its far end. On a first visit, the natural route is: square, parish, Casa de Moneda, Cockfight Arena (Palenque de Gallos) and the ruins of the Bullring. Here is the full list.