April really is a month during which you need a calendar in Brussels: Not only is the Flower show Floralia on and the bluebells in Hallerbos are in bloom but the Royal Greenhouses in Laeken are open too. This year they are open until May 8th, and if you can find the time, they definitely are worth visiting – even if you aren’t a real flower fan.
This short period is the only time of the year when you get to enter the grounds of the Royal Palace. But don’t expect to be able to wander through them entirely free. The visit takes you along a certain, cordoned path from the palace over to the fantastic green houses. They were designed by Alphonse Balat, the guy who was the Royal architect in the late 19th century. (He also rebuilt the Laeken Palace after a fire in 1890 and did a lot of work on the Royal Palace in town.) But Balat had a little helper at the time, the not yet famous Victor Horta who was his apprentice. For me, as a Horta-Fan, this was the main reason to visit the gardens. The steel-glass-constructions are amazing.
Royal Greenhouses of Laeken // Website