So wtf are these hunebedden that I've been talking about all day? Giant's beds. They rock!

Sorry, autocarrot. They are rocks. Specifically they are neolithic tombs that date from the time of the funnel beaker people. There are loads of them across the north of the Netherlands, into Germany, Denmark and into the Baltic nations. Where did the rocks come from? Scandinavia. Brought to the Netherlands by ice in an ice age 150k years ago.