Taking your valuables with you into a swimming pool is always a risk. The Romans should have paid better heed, judging from the quantity of gemstones recovered from the drain of one of their bathhouses.

As many as 30 semi-precious stones have been discovered by archaeologists almost 2,000 years after their owners lost them at a site in modern-day Carlisle, just behind Hadrian’s Wall.

The stones had dropped out of their ring settings, their glue probably weakened in the steamy baths. They were simply flushed into the drains when the pools and saunas were cleaned.