A rare Roman cavalry helmet found by a man using a metal detector in a northern English field sold for nearly 2.3 million pounds ($3.6 million) at a London auction Thursday.
The unusual bronze helmet, one of only three found in England, dates back nearly 2,000 years. The other two are in museums in London and Edinburgh.
The price was roughly eight times higher than had been expected. It was pushed up by six persistent bidders in the auction at Christie's South Kensington.
The helmet with face mask is described as an outstanding example of fine Roman metalwork. It was not designed for use in combat and would have been used during cavalry sporting events.
Georgiana Aitken, head of antiquities at Christie's, said the helmet is an amazing find.
"When the helmet was first brought to Christie's and I saw it firsthand, I could scarcely believe my eyes," she said. "This is an exceptional object."
The find is not covered by England's treasure law, which would have given the British Museum a special claim, so the unnamed finder is expected to be allowed to keep much of the proceeds from the sale.
A young man using a metal detector found the helmet in the northern county of Cumbria in May.