In 2014 a metal detectorist named Torben Christjansen unearthed a small Viking Age amulet on the Island of Lolland. Metal detecting is legal in Denmark, as long as artefacts are turned over to the National Museum, who study and catalogue each item found. It was found that this small Thor's Hammer dated to the 10th Century and was cast in Bronze with traces of silver and gold decoration.
Front and back of the Lolland Hammer (Source: National Museum of Denmark)
More amazingly the Hammer was inscribed with Runes, the form of writing used during the Viking Period. The translation work of the runic inscription was carried out by Lisbeth Imer from the National Museum and she concluded that the inscription was supposed to say 'This is a Hammer', but had a spelling mistake, possibly for reasons of space.
The Runic inscription on the Lolland Hammer. (Source: National Museum of Denmark)
This discovery is confirmation that similarly found archaeological Thor's Hammers are actual representations of the Mjölnir of Thor.