The absolute dating of historical buildings through thermally stimulated luminescence techniques involves also in situ and extra situ dosimetry techniques. The age calculation for brick sampled is obtained from the ratio between the absorbed dose through luminescence measurements and the annual dose through the U, Th and K contents and the environmental dose values at the sampling site. The radioactive contents of the sample and the environmental dose values can be used not only for dating purposes, but also to make assessments related to the level of natural radioactivity present in building materials in the case of historic buildings. The present study considered available data of samples from six sites in eastern Sicily. The analyses performed revealed a correlation between the environmental dose and the latitude of the sites from which the samples came and between the K and Th contents.