The construction of Terminal 5 at Heathrow, today the world's busiest international airport, was preceded by one of the largest archaeological investigations ever undertaken in the UK. Its scale has for the first time allowed the complex history of the Middle Thames Valley to be explored. This volume covers over 8,000 years of human history, including early prehistoric ceremonial activity, the introduction of farming and the imposition of administrative control in the Roman period. Borne of a unique relationship between heritage and development sectors, this is a new style excavation report. Designed to provide the reader with an accessible interpretation of the findings it also allows the coherency of those interpretations to be checked through the presentation of the detailed results of the excavations.