Jardin d'Agrumes du Palais Carnolès

Two hectares of citrus trees surround the former summer residence of the Princes of Monaco in Menton. The Jardin d'Agrumes du Palais Carnolès spreads across the Carnolès plain beside the old convent of La Madone. Its eighteenth-century palace carries the effortless air of a Trianon. Menton sits on the French Riviera near the Italian border, and the town owes its fame largely to lemons.

The story begins in 1725, when the architect Latour set large orange trees in a star pattern across a meadow. Prince Antoine I later added espaliers of lemon and Portuguese orange trees along the walks. The collection you see took shape in the 1970s, when the national agronomic institute from Corsica began testing varieties here. A partnership with the San Giuliano research station followed in 1997 and turned the grounds into a centre for acclimatisation. Around four hundred trees carry 137 varieties in one place. Sweet oranges account for 24 of those, with 6 bitter oranges and 6 lemons beside them. Grapefruits, clementines, mandarins, citrons and kumquats fill the remaining rows. That makes it the largest citrus collection in Europe, recognised by the French Conservatory of Specialized Plant Collections. The Bizzaria bitter orange stands out among the rarities, a variety the agronomic institute grows for grafting experiments. Twenty additions blend old names like Poire du Commandeur and Combava with newer crosses such as the Star Ruby pomelo.

Science happens among the trees, not behind walls. Ladybirds hunt aphids on the leaves, and two wasp species from Japan keep the Asian scale insect in check. Gardeners also battle mal sec, a fungus that has damaged lemon groves across the region. Contemporary sculptures rise between the beds, so art and botany share one walk. Serre de la Madone and the Jardin Botanique Val Rahmeh lie close by, extending a chain of gardens across Menton. The ground stays level from gate to gate, so you can trace a prince's star of oranges at an easy pace.