A six-storey block of offices and shops will be knocked down to make way for a public square in Cardiff city centre.
The demolition of St David’s House will involve the whole of Scott Road being closed for three weeks.
The work forms part of the wider Central Square development, which includes the new BBC Wales headquarters, HMRC building, and central bus station.
A statue of Wales’ first black headteacher, Betty Campbell, will feature in the new square created by the demolition of St David’s House. She was chosen by the thousands of people who voted in a BBC Wales poll, with the monument set to be unveiled in 2020.