The City of Miami's hapless Historic and Environmental Preservation Board actually managed to save a building once. It was back in 2001. The structure was the 75-year-old Firestone building at SW First Street and Twelfth Avenue in Little Havana. But as part of the deal, the guardians of the city's architectural flame decided to let Walgreens tamper with Miami's oldest sign, an 84-foot-long, 36-foot-tall, neon rooftop beauty that spelled out F-i-r-e-s-t-o-n-e. Walgreens recently opened shop inside the old service station, where generations of Miamians flocked for toys, bikes, and appliances, as well as tires and gas. The famous old sign now reads, W-a-l-g-r-e-e-n-s. The chain drugstore, however, did agree to use five of the original letters: two e's, an r, an s, and an n. Those letters, of course, spell sneer, which is about all that hardcore preservationists can do in this town.