A caprice, or also folly (English word for "folly" or "extravagance") or folie (French word with the same meaning as in English), is a building constructed primarily for decoration, but whose appearance suggests that it has some other purpose.

A contemporary example that makes use of folies as an articulating element of the organization of a modern urban park is the Parc de la Villette in Paris, by architect Bernard Tschumi.

Among the references of this type of work are the plastic whims "Capricho (art)") of Deiciochesco painting and engraving, where their authors use and represent images of ruins, architecture or real architectural elements but from combinations and contexts that they themselves manufacture. Among the famous artists who have developed this type of work, Pannini and Tiépolo stand out. In 1735, for example, Pannini developed his Roman Caprice: the Pantheon and other monuments, an architectural fantasy where he placed buildings and monuments of Rome in an unusually rural context.[1]​.

As small constructions, often of a romantic nature, architectural whims have different forms and functions: pavilion "Pavilion (architecture)"), tower, bridge, waterfall, ruins, grotto, shell house, rotunda, corners, they are built in a park or in a garden. Due to their arrangement and succession, they guarantee the articulation of the different areas and highlight the routes of the walks within the garden.

These are extravagant or whimsical buildings that emphasize artistic expression more than the functional aspect. The "factories" (built elements) that remain were hard-built, sometimes to look like an ancient building partially in ruins, however a large part of them were transitional constructions. Built with the help of wooden trellises, they served as decorations for specific country festivals.

Garden factories were very popular from the end of the century to the beginning of the century, together with the development of Romanticism and English-style gardens. Beyond their decorative aspect, the utilitarian aspect of these buildings was often neglected. For this reason, garden factories were sometimes described as "misunderstood buildings".[2]​.

The built elements of the garden ("factories") are generally grouped into four main picturesque typologies:.

Depending on the importance of the parks, the four groups cohabit or follow one another in the development of a walk and in the discovery of the garden. For example, in the English garden of the Little Trianon in Versailles, the walker crosses the rocks and grottoes, stops at the temple of love or at the Mirador "Viewpoint (architecture)") before reaching the Queen's Village and the group of cabins.