Silver Lyan occupies what was once the vault of the historic Riggs Bank. Today, the cozy space is lined with comfy red sofas. Its thick concrete walls are decorated with cabinets displaying trophies that glimmer in the low lighting. (The trophies are an unusual mix, including one awarded to “Last Place Champ.”) The vault’s original metal ceiling is still proudly on display. That room is perfect for larger groups, but if you just want to swing in and have a drink while soaking in the building’s history, walk-ins are always…