One forest that one needs to be visiting at least once in a lifetime (definitely if you’re from Belgium) is the Hallerbos, or “the Blue Forest”. The name may give it away: it’s located in Halle, in the province of Flemish Brabant (as this blog gives away) – and there’s also a little part in Walloon Brabant.
The forest is known in the region for its bluebell carpet which covers the forest floor for a few weeks each spring.
There are a lot of people visiting the forest at that time – so make sure you either come early, or hop on a bus from the train station till the entry of the forest.
There are other forests in Flanders where you can see some bluebells at the same time, so if you don’t want to see a lot of other people, maybe you can go to another one as well. But the forest is big enough for everyone that’s walking there. There were times that we saw a lot of people (and didn’t get anywhere because we had our little pup with us and everybody stopped and asked how old she was, what breed she was, …), but also some places in the forest where we hardly saw anyone else.