The Sunken Garden is a formal, traditional, English-style garden. It is enclosed by a shrub hedge and regional limestone terraces, which lend the garden the feeling of an outdoor room. An elegant 80-foot long reflecting pool provides a visual connection with Lake Monona. Mixed borders of cool colored flowering spring bulbs, annuals, perennials, and shrubs bloom from spring through autumn.
The Sunken Garden is Olbrich's oldest garden. It was originally a rose mall in 1952 and has since been transformed into the present day garden. The rectangular, symmetrical garden was named the Sunken Garden because of the two-foot drop from the edges of the garden.