Fig. 2From: Biodeterioration of Roman hypogea: the case study of the Catacombs of SS. Marcellino and Pietro (Rome, Italy)Sampling sites. a Site 1: a tufa corridor along the tourist path. c Site 2: ‘The Arcosolio of Orfeo’ covered entirely in frescoes. b and d Use of the MAT non-invasive sampling method at both sitesBack to article page