It’s time to plan that trip to Belgium, Road Trips Gardeners. The Royal Greenhouses will be open to the public from April 15, 2012, through May 8, 2012.

This is your only chance this year to get inside The Greenhouses in Laeken, Belgium — an Art Nouveau masterpiece that’s among the largest greenhouses in the world.

Designed by architect Alphonse Balat, with the help of his student Victor Horta, for King Leopold II, the greenhouses feature around 30 pavilions and a spectacular winter garden under a huge dome.

The site is open to the public just three weeks each year, making any visit just that bit more special. People go there as much for the beautiful architecture as the remarkable quality of the botanical collections. The tropical and subtropical plants include some of the world’s rarest camellias.

(Photo courtesy of Visit Flanders)