What was a common characteristic of the domus in Roman architecture?

In Roman architecture, the domus is characterized by its design, which typically includes a central courtyard, known as the atrium. This central space usually served key functions in the household, such as allowing light and air into the building, creating a social gathering area, and providing a transition between the private and public spheres of the home.

The design of the atrium also held symbolic significance, reflecting Roman values and social status. Often, the larger and more elaborately designed the atrium, the wealthier the family. The central courtyard was surrounded by various rooms, making it a focal point in the layout of the domus, which emphasized the importance of family and social interaction within the private domestic space.

In contrast, the other options do not accurately reflect the typical features of a domus. While some residences in ancient Rome could accommodate multiple families or include amenities such as gardens, the distinct and defining element of a domus is its central atrium. Open-air markets belong more to urban planning and public spaces in Roman cities rather than the residential architecture of the domus.