Viterbo was designed by Erik Deforce in the same year as the eye-catching modernist chaise longue Lord for the G-collection with which Deforce, as head of the Gervan seat manufacturer, presented itself at the 2nd international Interieur Fair in Kortrijk (B). Viterbo was a successful design from the start. The model Viterbo existed in several versions of nice fabrics or high quality leather. The seat was available as a one-, two- and three-seater, so that different combinations could be put together. Viterbo was particularly successful in the Netherlands. Reason why it can regularly be found there on the vintage market.

The Viterbo is sometimes confused with the famous Oriolo design for Luigi Sormani by Claudio Salocchi, on which it was clearly inspired and also a tribute. The important difference lies in the design of the legs of the armchair, which are elaborated in a playful angular shape at Deforce and an elegant arch shape at Salocchi. Deforce knew Salocchi personally from the time of his store Saga Design Center (1963-1970) in Ostend, where he was one of the first to introduce Salocchi's masterful designs to Belgium.