The 1400 block of Main Street is on the cusp of a transformation, but it wouldn’t be the first for the corner of Main and Washington. Before the current 13-story office tower went up in 1976, the site saw three different buildings come and go, starting with Columbia’s original city hall and market, which burned in 1865. Its replacement, a massive Italianate building with an opera house and library, was lost to another fire in 1899. In 1900, South Carolina National Bank built a new headquarters in the Beaux Arts style, complete with arched windows, stone columns, and a rooftop neon sign for SCE&G. The building at 1401 Main St. that stands today was designed by LBC&W and built by M.B. Kahn, which helped reshape the Cola’s skyline. Its glass curtain wall suspended from a steel frame set the tone for modern development downtown, influencing buildings that came after it. Soon, it’ll get a new pyramid on top…