The Orangerie is a massive greenhouse set into the hillside below the south terrace of the palace, designed by Jules Hardouin-Mansart in 1686. In winter it houses more than 3,000 trees — orange, oleander, laurel, palm, and bay — that spend the summer months in terracotta tubs set out on the Parterre du Midi above. The central hall is 155 metres long and lit by 17 large arched windows opening south.
Louis XIV was obsessed with oranges, which in 17th-century France were exotic luxuries. He reportedly had 3,000 orange trees, and serving fresh oranges out of season was a conspicuous demonstration of wealth and control over nature. The trees that stand in the Orangerie today are directly descended from those of Louis XIV's time; some of the oldest specimens are more than 200 years old.
The Orangerie is sometimes open for concerts and events, which gives a good excuse to see the interior. In summer, when the trees are outside and the building is less dramatic, most visitors walk past without entering. In winter or early spring, with the trees brought back inside and the light filtering through those great south windows, it is one of the more unexpected pleasures of the estate.