have announced the discovery of two long alignments of wooden posts in the Iron Age cult site of Uppsala. One of them is more than a thousand yards (900 m) long, with posts holes at regular 20-foot intervals. The other is about half as long. Animal bones were found in some of the post holes, suggesting that sacrifices were performed when the posts were set up. The posts were quite large, and the excavators think they may have been as tall as 23 feet (7 m).
One problem with interpreting prehistoric stone monuments, like Stonehenge or Carnac, is that we don't know how many similar constructions there once were in wood.