hut made of tree trunks on stone age playground of neanderthal museum, mettmann, germany.

neanderthal museum mettmann prehistory early history mankind neander valley bone parts found human bones traces reconstructions finds founds cave caves excavages spears playground carved sturdy tree trunks support net structure climbing german creative children kids boys girls extraordinary play playing dusseldorf neandertal humans rusty steel sculptures stone age germany hut germany