The most ancient known half-timbered building is called the House of opus craticum. It was buried by the eruption of Mount Vesuvius in 79 AD in Herculaneum, Italy. Opus craticum was mentioned by Vitruvius in his books on architecture as a timber frame with wattlework infill. However, the same term is used to describe timber frames with an infill of stone rubble laid in mortar the Romans called opus incertum.