'Tile-tapping' test conducted at the Sydney Opera House(1/4)

Workers carry out the "tile-tapping' test" at the Sydney Opera House, April 5, 2022, Sydney, Australia. Every five years maintenance workers spend six weeks inspecting a tap test on each tile on the sails of the Sydney Opera House. (Photo/VCG)

A worker carries out the "tile-tapping' test" at the Sydney Opera House, April 5, 2022, Sydney, Australia. Every five years maintenance workers spend six weeks inspecting a tap test on each tile on the sails of the Sydney Opera House. (Photo/VCG)

A worker carries out the "tile-tapping' test" at the Sydney Opera House, April 5, 2022, Sydney, Australia. Every five years maintenance workers spend six weeks inspecting a tap test on each tile on the sails of the Sydney Opera House. (Photo/VCG)

A worker carries out the "tile-tapping' test" at the Sydney Opera House, April 5, 2022, Sydney, Australia. Every five years maintenance workers spend six weeks inspecting a tap test on each tile on the sails of the Sydney Opera House. (Photo/VCG)