How Ancient Romans Kept the Colosseum Cool in Sweltering Heat

Rome is one of the hottest cities in Europe during the summer. Spare a thought, then, for the citizens of the Roman Empire, when lack of shade meant they had little choice but to bake in sweltering conditions.

One place where Romans could find some refuge was the Colosseum. The iconic amphitheater had a retractable awning, known as a velarium, that covered most of the seats and allowed visitors to watch bloodshed in relative relief. “It was crucial for the comfort of the spectators,” says Kristin Triff, who teaches architectural history at Trinity College. 

But the Colosseum wasn’t the first event space to have its own retractable roof, explains Edward Watts, a Roman history professor at University of California San Diego. “The first examples we have of it are actually in Greek theaters. Romans leaders then copied this approach,” he says.

Ancient author Pliny The Elder credits Quintus Lutatius Catulus, a consul in 102 B.C., with first putting shade over a Greek theater, says Paul Belonick, author of Restraint, Conflict, and the Fall of the Roman Republic. 

Pompeii’s amphitheater, built around 70 B.C., also had its own velarium that was anchored into the nearby walls of the city, rather than the building itself. “[Roman poet and philosopher] Lucretius even writes about the beautiful fluttering and dancing of the linen from velarium,” Triff says.

As one of the Roman Empire’s most ambitious construction projects, the Colosseum was designed to include a velarium before it opened in A.D. 80.

The velarium at the Colosseum consisted of over 200 huge masts that were fixed into sockets around the top edge of the structure. Strips of linen were attached to both the masts and a pulley system of ropes. These ropes were operated by winches, which moved the linen back and forth over the seated areas inside the stadium. 

Given the similarities between a velarium and a sail on a ship, hundreds of the finest sailors from the Roman Empire were ordered to work these winches. “They’d be up on the top story of the Colosseum working the masts,” Triff says. “They’d have to work in sync, and it had to be coordinated.”

“They were from the imperial fleet that was based in Misenum,” explains Watts. “They were brought in to operate it because they had experience measuring wind, understanding how wind worked with cloth and making sure the apparatus didn’t break. You really did need to have qualified people operating this.”

The sight of the velarium as it was unfolded quickly became a part of the theatrical experience presented at the Colosseum. Some rulers wanted everyone to be seated and the velarium unveiled before events could begin. “My sense is that the opening of the velarium was an event itself. The audience would watch it happen in wonder,” Triff says.

It wasn’t only the sight of the awning that impressed attendees. According to Belonick, Lucretius described the dramatic sound of the velarium as it unfurled and its support beams snapped into place. He compared the noise to thunder.

While it’s believed that the velarium covered most of the seating area of the Colosseum, people near the arena floor were less likely to be shielded from the sun. This meant that some senators sitting closest to the action were left exposed to the blistering heat, notes Watts.

One of the reasons why the curtain didn’t go all the way across the arena is because they wanted the hot air to go out through the middle of the velarium. The heated air rushing to get out of this smaller opening “would create a breeze,” Triff says. “You could say it was akin to Roman air-conditioning.”

According to legend, Caligula—who ruled decades before the Colosseum was built—was so annoyed on one baking hot day inside an amphitheater that he told the sailors not to put the velarium over the crowd and prevented people from leaving. Instead, they sat inside and were subjected to the intense heat from the sun as a display of Caligula’s power.

Velaria were used to convey messages of power and authority in other ways, too. Emperor Nero is believed to have painted images of the heavens and stars on a velarium, while Watts predicts that other rulers would have made their awnings colorful, “because everything in the Roman world was colorful.” He adds, “It had to be aesthetically pleasing because everything was about displaying the glory of the people putting on the games.” 

This is also why the velarium was put on the marketing material for events at the amphitheaters, says Belonick. Papyrus flyers and graffiti would promote how much shade would be at the games. “They wanted people to know that it would be a comfortable experience,” Belonick continues. “Again, it’s a form of advertising. They want people to know that the velarium was expensive and that the awnings are part of the show. It worked, because people were really happy that they got to go and sit in the shade.”