With historic buildings, an arts district and a lively street scene reflecting its thriving Latino population, Santa Ana has grown into the slogan it adopted in 2006: “Downtown Orange County.” It’s come a long way since the ’80s, when the civic center area was a ghost town of boarded-up buildings. Now, in a county known for its suburban sprawl, Santa Ana is a true urban center, with an art walk the first Saturday of every month…