The Palais Garnier in Paris is among the world’s oldest theaters that still functions more or less in its original state. And long before the appearance of the selfie-stick, the Garnier was a place not just to see art, but to be seen.

At a 150th anniversary gala on Friday, before guests reach the marble staircase, the baroque sculptures, the inlaid golden mosaics and the elaborately painted ceiling, they will pass two giant mirrors set on the ground floor.

These were the architect Charles Garnier’s gift to season ticket holders, for a quick once-over before they stepped onto a marble catwalk beneath four levels of viewing galleries.

“They were there to give them some psychological reassurance. To look at themselves and say, ‘Everything is good. You are ready,’” said Sandrine Lamiable, a Palais Garnier tour guide leading a group of tourists up the marble steps earlier this month. “Then, they were plunged into a veritable palace, as princesses and princes.”

The point of the Garnier Opera building was never just the show onstage. It was the show of being on display, particularly for the rising bourgeoisie that had profited off France’s booming industrial revolution.

“The point of the opera was to parade, for the elites of the time to offer a spectacle: themselves,” said Lamiable.