Flag Fen

Flag Fen, east of Peterborough, England, is a Bronze Age site which was constructed about 3500 years ago and consists of more than 60,000 timbers arranged in five very long rows, creating a wooden causeway across the wet fenland. Part-way across the structure a small island was formed. Items associated with it have led scholars to conclude that the island was of religious significance. Archaeological work began in 1982 at the site, which is located 800 m east of Fengate. Flag Fen is now part of the Greater Fens Museum Partnership. A visitor centre has been constructed on site and some areas have been reconstructed, including a typical Iron Age roundhouse dwelling.

Source: Wikipedia