Under the London pavements are the city's lost rivers, hidden in tunnels and sewers. The most famous, the Fleet, runs straight through central London just below the surface, but few know it is there. Follow the lower Fleet from St. Pancras to Blackfriars with Tom Bolton, author of London's Lost Rivers, and hear how the river ran with blood, cured the sick, shaped the city and entered London myth. The walk is 3.5 miles long, and will last around 2.5 hours, ending at Blackfriars Bridge.