Traditionally, a handheld censer is used during Catholic Mass to burn incense as an “oration to God” and as part of rituals in the Orthodox religion. Historically, the incense also served to mask the smell of tired and unwashed pilgrims who crowded into the pews. It was also believed to have a preventative effect against plague.

But when a cathedral is the size of the Santiago de Compostela Cathedral in Spain—which has a capacity of 1,200 people—an altar boy swinging a mere incense burner won’t cut it. That’s where the Botafumeiro comes in. At 5.25 feet tall and with a reported weight of between 110 to 352 pounds, this thurible is one of the largest in the world.

The cathedral has used a swinging censer since the 11th century. Its size necessitates the use of a rope and pulley system, its current one having been installed in 1604. At a cost of about 450 euros per “performance,” the Botafumeiro isn’t swung at every mass. When it’s brought out for special occasions, it requires eight red-robed men called tiraboleiros to swing it. It can reach heights of 69 feet at the top of its 213-foot arc between the ends of the cathedral. It can reach its maximum height after about 17 cycles, which requires roughly 80 seconds of swinging.

A massive swinging piece of metal is, of course, not without its accidents. The most notable occurred when Princess Catherine of Aragon visited in 1499 on her journey to marry Arthur, Prince of Wales and son of King Henry VII. While it was being swung, the Botafumeiro became disconnected from its rope and flew out of the cathedral through a high window. Luckily, no one is believed to have been injured by the rogue, man-sized incense burner.

More recently, the cords holding the Botafumeiro failed in July 1937 and hot coals toppled onto the floor. But modern-day pilgrims and tourists can rest assured: the current procedure is to attach the rope to the Botafumeiro with sturdy sailor’s knots.