La Longue Rocque
Guernsey
La Longue Rocque is the tallest megalithic menhir in the Channel Islands. A granite block 3.5-metre (11 ft) tall and extending a further metre (3 ft) below the ground, it stands in a field next to Les Paysans road in Guernsey. It is believed that it was erected between 3000-1500 BC.
Monument data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).