Charcoal production in forests is one of the oldest forms of forest exploitation. The legacy of such once widespread activity is a plethora of relic charcoal hearths (RCHs1), where soil shows a thick, black, charcoal-rich top horizon. Even where very common, such as in European forests, RCHs were rarely studied to assess their relevance as C reservoir. For this purpose, as a case study, we investigated some RCHs at Marsiliana, a typical Mediterranean oak forest from Central Italy. We found that RCHs soils, in spite of representing < 0.5% of total surface, gave a substantial contribution in terms of C, i.e. 1.1% to 4.2% of total ecosystem C, including litter, the top 30 cm of soil, deadwood, above-ground and below-ground biomass. On average, soil C content in RCHs was eight times higher than the soil outside the RCHs. The environmental significance of RCHs soils appears still greater considering that, on average, 43% of their C stock was charcoal, a form of C highly recalcitrant to mineralization. These results would stress the importance of accounting for the contribution of RCHs in terms of soil C and giving an estimation of their charcoal content in future C inventories, both as macroscopic and microscopic particles in soil. This study support the necessity of safeguarding the anthropogenic soils of RCHs as a precious C reservoir as well as a memory of past land uses.