https://www.hoptondentalsurgery.co.uk/contact/ In the United States on September 11, we mourn the horrific tragedy that occurred on that terrible day in 2001. In the region of Catalonia, it is the National Day of Catalonia, or La Diada, which also is a remembrance day, the day that Barcelona fell to the Bourbons and Catalonia was forced to become a part of Spain.