‘Guerco’ – A ‘Guerco’ (digger) inside a ‘Bottino’ (the name probably derives from the barrel shape of the vault) frightened Sienese, bewildered by the appearance of ‘Fuggisoli’ and ‘Omiccioli’: the underground work, by the mere light of faint lights, caused fears, anxieties and visions such as the presence of fantastic creatures.