Mas de l'Obac Vell

Mas de l'Obac Vell is a set of farmhouse ruins in the municipality of Vacarisses, in the Vallès Occidental county of Catalonia, sitting at roughly 680 metres above sea level. The name comes from "obac," the shaded northern side of a slope, as opposed to the sunnier "solà" across the valley — a naming pattern common across rural Catalonia.

How do you get there?

Start from the road linking Terrassa and Rellinars. Just before the Coll de l'Obac pass, around the 9th kilometre, a track branches off toward Casa Nova de l'Obac, the newer farmhouse that eventually replaced the old one. From there, a path heading north for about 800 metres brings you to the old ruins. The whole route sits inside the Sant Llorenç del Munt i l'Obac Natural Park, so sturdy footwear and a trail map are worth carrying, since signage on the ground is sparse.

What will you find on site?

Rather than a single intact building, the site is a cluster of walls and foundations from several periods. Some elements may go back to Roman or Visigothic times, and building work continued in phases until the 18th century, when the Ubach family finally left for Casa Nova. The main house structure visible today dates to 1571.

The most distinctive feature is a square tower crossed by a barrel-vaulted passage, with a cylindrical turret attached to it — an unusual combination for a rural building in this area. Sections of the surrounding quadrangular wall were built using opus spicatum, a herringbone stone-laying technique inherited from Roman construction and still used in the early Middle Ages. That masonry detail is usually what draws the attention of visitors interested in building history.

The site is registered as an asset of local cultural interest, and archaeological digs have taken place here in recent years — the Vacarisses town council has reported on further excavation phases aimed at clarifying the building's timeline. Nearby stands the Pou de Glaç de l'Obac Vell, an old ice well that hints at how this hillside was put to economic use long before refrigeration existed.

When should you visit?

Thanks to the altitude and the shaded orientation, summers here stay noticeably cooler than down in the Vallès valley, making it a sensible escape on hot days. Spring and autumn are the best seasons for longer hikes through the natural park, with mild temperatures and fewer crowds than in summer. Winter visits can mean muddy paths after rain, so it helps to check the forecast beforehand.

Frequently asked questions

Can anyone visit the ruins? Yes, the site lies within the natural park and can be reached on foot, though there is no visitor infrastructure or on-site information panels, so it helps to read up before heading out.

How long is the final stretch on foot? From the junction near Coll de l'Obac to the ruins is about 800 metres, a walk of roughly fifteen minutes, though reaching that junction itself usually requires a longer hike or a drive along local roads.

What's the difference between Mas de l'Obac Vell and Casa Nova de l'Obac? Casa Nova is the newer farmhouse the Ubach family moved into during the 18th century after abandoning the old house. Both stand close together on the same hillside.

What is the opus spicatum visible in the walls? It's a masonry technique where stones are laid at an angle in a herringbone pattern, used from Roman times through the early medieval period.