Which item was primarily used by Roman citizens to indicate time during the day?

The sundial was primarily used by Roman citizens to indicate time during the day because it relies on the position of the sun in the sky, which changes throughout the day. This ancient device consists of a flat plate marked with hours and a gnomon, which is a stick or a triangular blade that casts a shadow. As the sunlight moves across the dial, the shadow of the gnomon falls on different hour marks, effectively allowing users to tell the time based on the sun's position.

While other devices like the water clock (or clepsydra) were also used for measuring time, they were typically employed for measuring intervals of time rather than indicating the exact hours of the day. Candelabra, on the other hand, were primarily used for providing light, and while they could serve to estimate time at night, they were not a primary tool for tracking the time during daylight hours when the sundial was readily available and effective.