Sophistication of the Menga Dolmen in Spain; DNA of Slavic migration; world’s oldest fortress in Siberia; unusual Wari Empire complex

Neolithic builders used simple tools, complex planning to build the Menga Dolmen

DNA research shows Slavic migration into the Balkans began in late Roman times

In Siberia, world's oldest fortress challenges view of how societies developed

Ruins of first rural Wari Empire complex unearthed in Peru