As I mentioned before, I'm quite interested in megaliths.
You surely know the ones in Stonehenge (United Kingdom) or Carnac (Brittany, France) and people who visited Brittany have surely stumbled over a number of other megalithical structures too. Brittany is very well known for its menhirs, cromlec'hs (or stone circles), alignements, tumuli (burial mounds) and dolmens (on the contrary to what Wikipedia claims they are not the same as cromlec'hs). I learned about that as a boy via comics I used to read (Asterix by Uderzo and Goscinny) and once I had my own car and could decide for myself where I would take a holiday I drove off to Brittany and started "chasing" these prehistorical monuments.
Only years later I learned that in a region much closer to mine there were plenty of megalithical structures too: Drenthe in The Netherlands. No menhirs, cromlec'hs or alignements there, but the region is very big on hunebedden. That's the Dutch word for dolmens and it means "beds of giants". There's 52 of them remaining in this region which is not even 2700 square kilometers big (thats 1042 square miles). The only other region in The Netherlands where you'll find megalithical structures is Frisia, which has ... one (and that one is in a museum).
There's also an enormous number of tumuli in Drenthe. You'll find those burial mounds in many other places in The Netherlands too (I found out about that even more recently), but they are very concentrated in the Drenthe region.
And the thing is: they are not tourist traps. As a matter of fact, when you visit a hunebed, you'll rarely see another visitor. The Dutch don't hide these monuments (they are way too big to hide, most of them are bigger than the ones you'll find in Brittany), but they are not romantic about it (you'll notice that they are named with a letter and a number - "D" for Drenthe and the number coming from professor Van Giffen who indexed and in some cases restaured them - while nearly all the megalithical structures in Brittany and elsewhere have got some actual name), maybe that's why. Anyway, even megalith hunters are often surprised that there are megaliths in The Netherlands (I was in a group on Google+ where people knew about the few structures in Wallonia, Belgium, but not at all about the many structures in The Netherlands).
So, after the series of megaliths in Brittany (here, here and here), here's a series about the megalithical structures in Drenthe. And here's a page on which you can read more about the Dutch dolmens.