Drenthe contains 54 of the Netherlands' 55 surviving hunebedden — prehistoric megalithic tombs built from boulders deposited by glaciers during the last ice age, constructed around 3000 BCE. Several lie within cycling distance of Ruinen, scattered across heathland and woodland in the typically understated Drenthe way: you find them at the end of a path, often without fencing or interpretation, just enormous stones arranged with quiet purpose.
De Zaandplatte, just east of Ruinen, is one of the more accessible examples. The Hunebedcentrum (Hunebeds Centre) at Borger, about 25 kilometres northeast, provides the best overview of all 54 monuments with good exhibits and cycling routes connecting them. The monuments are free to visit and open at all times. The experience of coming across a four-thousand-year-old megalith in the middle of a Dutch heath — with no one else around — is one of those travel experiences that properly shifts your sense of time.