Complex sentence: The name Traitors' Gate has been used since the early seventeenth century, prisoners were brought by barge along the Thames, passing under London Bridge, where the heads of recently executed prisoners were displayed on pikes.
Split into simpler sentences: The name Traitors' Gate has been used since the early seventeenth century. Prisoners were brought by barge along the Thames, passing under London Bridge, where the heads of recently executed prisoners were displayed on pikes.