The Vallès Occidental Regional Archive (ACVOC) was created in 1982 as an archive dependent on the Generalitat de Catalunya. Its location in Terrassa was in keeping with the city's long tradition in the field of archives. Currently, the ACVOC also includes the Terrassa Historical Archive, created in 1932.

The Vallès Occidental Regional Archive - Terrassa Historical Archive holds a total of 315 documentary collections, with a volume of 5,466 linear metres of documentation originating from local, royal and stately administration, notarial, religious, business and private. It also has a further 250 linear metres of auxiliary and administrative library. The oldest document held in this archive is a fragment of a codex with Visigothic writing dating from the 9th century.

The new and modern building that houses the archive, inaugurated on June 9, 2014, has a surface area of ​​3,800 m2, and is divided into three basic areas. A first area is located on the lower floor, and has five conventional deposits plus a sixth for special formats. There is also an area of ​​three deposits on an upper floor, with a loading and unloading dock and a disinfection, cleaning and storage section. Finally, there is a main area with a conventional deposit, an internal work room, a digitization room, two refrigerated deposits for the preservation of photographs, an external work room, a very spacious public consultation room, a space for training activities and a large-capacity multipurpose room.

The new facility aims to preserve, conserve, process and disseminate local and regional documentary heritage, which is why it incorporates digital processing tools. The ACVOC also plays an important role as a cultural and social agent at the service of Terrassa and the Vallès Occidental. In addition, it also advises the administrations in its area that request it on matters of document management and the implementation of document management systems. This function covers documentation in both traditional and electronic media, as well as digitized documents.