The sumptuous 18th-century Pupp covers nearly the whole of the spa's southern end and oozes old-world glamour. It was featured in the James Bond film Casino Royale and inspired Wes Anderson's Grand Budapest Hotel. These days it's a budget-blower, but worth the splurge if you can snag one of the rooms in period style (you have to ask).
Even if you're not staying here, take a peek inside; the restaurants are very good, and the historic atmosphere is perfect.