Tony Robinson, the star of television programme Time Team, dropped in on Welwyn to help dig a hole. Welwyn archaeologist Tony Rook lent a hand as the team filmed footage for Time Team's The Big Dig, in gardener Kim Wilde's garden on Friday.
Mr Rook said the garden would have belonged to St Albans Abbey at one point. Herts County Council archaeologist Stewart Bryant said they were unsure what they would find in the test dig, which measured one metre square.
Director Laurence Vulliamy said: "This is for The Big Dig, a series of programmes being made to celebrate 10 years of Time Team. We are encouraging people at home, people in their gardens, schools, colleges, companies, to sink holes where they think there is something of interest.
"We don't want to encourage people to put test pits just for the sake of doing it, but for real archaeological purposes. The hole will be recorded, we will mark its position and what factors may appear, then it will be backfilled and closed up."
Mr Vulliamy said the filming will make up one of a series of programmes, which will go out between June 22 and 29, for Channel Four.