Brussels 17 April 2015 In 1873, architect Alphonse Balat designed for King Leopold II a complex of greenhouses which complement the castle of Laeken, built in the classical style. The complex has the appearance of a glass city set in an undulating landscape. The monumental pavilions, glass cupolas, wide arcades that cross the site like covered streets, are much more than an anecdote on the architectural applications of iron and glass or on little greenhouses of exotic plants. Like each year at the same season, the greenhouses at the Royal Castle of Laeken opened to the public during almost three weeks. This tradition has been carried on for a century. Credit Frederic Sierakowski / Isopix