Time Team visits the heart of Wiltshire for one of their most ambitious projects ever: to investigate an entire lost Roman town. Hidden under acres of wheat, Cunetio would once have been a bustling market centre. It's also the place where Britain's largest ever coin hoard was found. In the 1970s a pot containing 55,000 Roman coins was discovered, and one of the archaeologists called in to deal with it was Time Team's own Phil Harding. Now, 30 years later, he's back to dig this massive site and to find out how much effort is required to bury 55,000 coins. Over the three days, the scale of the site pushes the Team to the limit. Hampered by driving rain, the archaeologists battle to make sense of trenches that contain hundreds of years' worth of archaeology, while the geophysics team make almost half a million readings to complete the biggest survey ever recorded on Time Team.

• Tim Taylor

• Tony Robinson
• Bill Oddie
• Phil Harding