The Romans began constructing paved roads shortly after their invasion in AD 43. The London portion of Watling Street was rediscovered during Christopher Wren's rebuilding of St Mary-le-Bow in 1671–73, following the Great Fire. Modern excavations date its construction to the winter from AD 47 to 48. Around London, it was wide and paved with gravel. It was repeatedly redone, including at least twice before the sack of London by Boudica's troops in 60 or 61. The road ran straight from the bridgehead on the Thames to what would become Newgate on the London Wall before passing over Ludgate Hill and the Fleet and dividing into Watling Street and the Devil's Highway west to Calleva (Silchester). Some of this route is preserved beneath Old Kent Road.