In early 2013, 9 W. Broad St. on the edge of downtown Stamford languished as an empty and neglected property. Today, it hums with activity as some 400 workers stream in and out of a refurbished nine-story structure. Stamford and other communities in southwestern Connecticut still grapple with office vacancy rates hovering above 20 percent. But the revitalization of 9 W. Broad St. and the turnaround of similar buildings show how property owners’ capital investments and the draw of central locations can make corporate hubs attractive to tenants in a challenging market. “There is a little reticence in the market to being that first tenant in, so the owner has to prove themselves,” said, principal of in Norwalk, a firm that represents tenants in commercial real estate transactions.