The Old Post Office Restaurant and Inn, built in the 1690s, is the oldest surviving building in Debrecen. It was the house of Samuel Diószegi, the town's first postmaster, and also served as the town's post office. Its most notable guest was King Charles XII of Sweden, who arrived in Debrecen on 13 November 1714 and stayed at the Inn. He was pleased to note that 'in that remote town' there was a well-stocked library. The event is commemorated on the street façade of the building by a relief plaque depicting King Charles XII of Sweden by Richard Füredi.