Travnik’s 15th-century fortress surveys the city from a shoulder of hillside above Plava Voda. The stone walls gleam so brightly in the sunshine that they appear to have been scrubbed. The restored multisided keep houses a modest museum of local history and folk costumes. Travnik is much more historically important than it appears at first glance. Travnik, in fact, was long the seat of Bosnia’s Ottoman viziers.