Roman aqueduct from the 16th-century
You know that the medieval will be the theme of the day from the moment you near the parking lot at the town entrance. A grand introduction is made by the arches of a 3km long stone aqueduct. What you cannot see are the additional 3km of underground tunnels that go on to connect to the source of the water.
This marvel of Roman engineering dating back to the 16th-century was funded by the vaults of Queen Catherine. So important was the project for the people of Obidos, that she even sold her surrounding land to fund its construction. It turned out to be money well spent. Even today, the aqueduct is in impeccable condition.