Plaza de Mayo commemorates the historic Battle of Puebla . Much of the Southwestern U.S. was once part of Mexico . Many historical sites in Texas , Colorado and beyond . Mexico took over the downtown after the country won its independence from Spain in 1821 . Old Town San Diego is hosting the Cinco de Mayo this year .
Plaza de Mayo commemorates the historic Battle of Puebla . Much of the Southwestern U.S. was once part of Mexico . Many historical sites in Texas , Colorado and beyond . Old Town San Diego is hosting the Cinco de Mayo this year .