Hierarchy classification:

1. top of the aat hierarchies
2. Objects Facet
3. Built Environment (hierarchy name)
4. Single Built Works (hierarchy name)
5. single built works (built environment)
6. [single built works by specific type]
7. [single built works by location or context]
8. garden structures

Anotations

Scope note:

Refers to artificially constructed garden features, common since the 16th century in French and English landscapes. A grotto is characterized by being an excavation or structure made to imitate a rocky cave, often adorned with shell-work, colorful stones, etc., and serving as a place of recreation or a cool retreat. For natural features, use "caves" or "caverns."