Carlo IV occupies a splendid building in Prague that was originally constructed in the 1890s for the Czech Mortgage Bank, as can be seen from the inscription over the front door: Hypotecni Banka Ceska. Designed by the famed Viennese architect Achille Wölf, it is among the most interesting buildings of the late 19th-century neo-Renaissance style in the Czech Republic – the others being the National Museum and the National Theatre. The façade is decorated with metal reliefs representing the evolution of coinage in the Czech kingdom. During the Communist regime, it became the headquarters of the Czechoslovakian Postal Service.
Its conversion to a luxury hotel was led by two outstanding interior architects: Maurizio Papiri and Adam D Tihany. Within the hotel, many original features have been preserved or restored. The original bank treasury room, complete with Wertheim wrought-iron doors, functions today as The Vault Bar. The hotel lobby – where once the bank tellers worked – has been restored and its original frescoes preserved. The adjacent modern building is the work of Prague's design atelier DaM and talented Czech architects Richard Dole and Petr Malínský. The modern part of the hotel is covered in glass frames decorated with green and red leaves.