The Brahmins who built the Old Colony Trust Co. bank in 1890 would probably faint dead to see its current incarnation, the very soul of contemporary decadence. During the 2001 makeover, Mantra's basic infrastructure was kept intact, so today the 30-foot teller's counter makes an elegant bar. Expanses of gorgeous Italian marble splotched like a Brittany spaniel also remain as vestiges of the space's earlier incarnation. But to imbue the room with modernity, the trendy interior design team poured on such stylish touches as chain-mail curtains, leather flooring, raw-silk fauteuils and a Jenga-like sculptural hookah/cocktail den with red suede banquettes.