The prop­er­ty includes the min­ing sites of Almadén (Spain), where mer­cury (quick­sil­ver) has been extract­ed since antiq­ui­ty, and Idri­ja (Slove­nia), where mer­cury was first found in AD1490. The Span­ish prop­er­ty includes build­ings relat­ing to its min­ing his­to­ry, includ­ing Reta­mar Cas­tle, reli­gious build­ings and tra­di­tion­al dwellings. The site in Idri­ja notably fea­tures mer­cury stores and infra­struc­ture, as well as min­ers’ liv­ing quar­ters, and a min­ers’ the­atre. The sites bear tes­ti­mo­ny to the inter­con­ti­nen­tal trade in mer­cury which gen­er­at­ed impor­tant exchanges between Europe and Amer­i­ca over the cen­turies. Togeth­er they rep­re­sent the two largest mer­cury mines in the world, oper­a­tional until recent times.