Terrassa has many layers of past civilisations dating back to the Pleistocene, but it was at the beginning of the 12th century and during the 13th that it was born around the current Torre del Castell Palau.

The growth of the population and the strengthening of the municipal structure produced the urban expansion outside the walls of the medieval town. In the middle of the 19th century, a period of industrial expansion began and the population increased considerably. The industrial transformation of the 19th century meant the introduction of mechanical innovations in Terrassa. Communications improved considerably, with the construction of the road to Barcelona in 1845 and the connection to Barcelona by railway in 1856. Industrial progress led to an increase in commercial businesses and a population growth that forced the demolition of the walls in 1876. The industrial development experienced by the city and the interest in the culture of the bourgeoisie from Terrassa boosted the Catalan Art Nouveau movement of which some buildings are preserved. The economic crisis of 1974, however, paralysed this industrial process and gave rise to a new economic fabric.

From the end of the 20th century, a new stage of prosperity and orderly urban growth began with eco-social transformation projects such as the Green Ring.