Bulgaria

Bulgaria's pair is a capital and a city that outdates it by several thousand years. Plovdiv is built over Thracian, Roman and Ottoman layers and claims continuous habitation of some eight thousand years, with a Roman theatre still used for performances; Sofia sits below a mountain within a tram ride of the centre and keeps a fourth-century rotunda in a courtyard between government buildings. Both are cheap to reach and under-described, which the atlas treats as a fact about coverage rather than about the places.