The Shard is bringing in a team of lawyers to investigate after staff found a pair of women's black knickers in the men's lavatories at the 68th floor viewing platform of Britain's tallest skyscraper.
The finding led staff to believe visitors to Europe's second tallest building may have been having sex in front of the full-length windows offering superb views across the capital.
A spokesman for the Shard said they were bringing in lawyers to investigate the allegation. He added that the underwear could have been "planted".
"There is absolutely no evidence people were having sex," he added.
Staff reportedly found the underwear after an exclusive party and they fear more couples may choose the skyscraper for their amorous encounters once the viewing area, known as the View From the Shard, opens on February 4.
The practice has been dubbed the 'almost mile high club'.