What is a rotunda characterized by?

A rotunda is characterized by being a round building, which is a defining architectural feature of this type of structure. Typically, rotundas are significant in design and may be used for various purposes, such as public spaces, churches, or government buildings, often enhancing the aesthetic appeal with their circular forms. The rounded shape allows for unique interior designs and can create a sense of spaciousness.

In contrast, the other choices describe different architectural forms. A square building with multiple stories does not align with the round nature of a rotunda. While a building with a pyramidal roof could refer to diverse architectural styles, it lacks the essential round characteristic that defines a rotunda. The colonnaded area of a temple refers specifically to the columns that support a structure, which does not relate to the defining feature of being a round building.