Alco Castle, 18th-century folly in Montpellier, France

Alco Castle is an 18th-century residence with a symmetrical garden layout spread across two levels, connected by a double staircase structure. The grounds feature multiple pools and fountains integrated throughout the landscaped property.

Built around 1740 for Antoine-Samuel Bonnier, a tax farmer from a family of drapers turned financiers, the residence is documented as early as 1744. The owner took the name Bonnier d'Alco, while a relative who built the Château de la Mosson became Bonnier de La Mosson. The Hérault departmental council bought the estate in January 1980 and restored it between 1985 and 1989.

The name Alco was adopted by Antoine-Samuel Bonnier, the financier who built the house around 1740, as his family name became Bonnier d'Alco; a relative who built the Château de la Mosson was called Bonnier de La Mosson. The house is a small Louis XV country residence rather than a monumental folly, with a narrow false avant-corps crowned by a low semicircular pediment. In 1937 the writer Léandre Vaillat noted how its tile roof and pink render were chosen for the Languedoc light.

The building serves primarily administrative functions, with a restaurant area on the ground floor for departmental staff. Access and hours may vary depending on official usage and current operations.

The outbuildings that once surrounded the courtyard were built for winegrowing, and the estate stood among vineyards; by 1937 the writer Léandre Vaillat could still praise how its tiled roof and pink render answered the Languedoc light. Housing and villas have since replaced the vines.