What was the name of the large awning that shaded spectators?

The large awning that shaded spectators at the Colosseum was called the velarium.

The name comes from the Latin velum, meaning “sail” or “curtain.” Rather than being a solid roof, the velarium was a retractable, canvas-covered network of ropes stretched over much of the seating area. It protected spectators from intense sun and probably helped create airflow through the amphitheatre.

The system was an impressive piece of Roman engineering. Around 240 mast supports were placed along the Colosseum’s upper rim, and sailors from the Roman fleet at Misenum were traditionally assigned to operate the ropes and rigging. The awning did not necessarily cover the entire arena, and scholars still debate exactly how far it extended.

A common mix-up is to call it simply a “canopy.” That describes its function, but velarium is the specific historical term. Similar awnings were used in other Roman amphitheatres, although the Colosseum’s was exceptionally large.