Sarah V.
Yelp
I highly recommend visiting the royal gardens/greenhouses! The garden and grounds of the palace in Laeken are stunning, it is amazing to see all the different plants, trees, bushes, flowers, etc. that are grown, both exotic and native plants. One of my mother's favorites, geraniums, grow around 1.5 meters in the greenhouse! I have never seen them grow so tall. It is truly breathtaking to see.
If you have an afternoon or morning free, whether tourist or native of Belgium/Brussels, I suggest taking a look here! Make sure to go quickly, it is only open 3 weeks out of the year...price is 2,5 eur per person and under 18 is free (family friendly!). I went the second day it was open and the weather was gorgeous, surprisingly, the lines and crowds were not bad in the least.