Work will start next week reopening a dock feeder canal running through the centre of Cardiff.
The year-long project will revive the canal underneath Churchill Way
The project forms a key part of Cardiff Council's Canal Quarter masterplan in the eastern end of the city centre, and eventually the canal will extend down to Tyndall Street.
The top end of Churchill Way, north of North Edward Street, will be closed to traffic, while Station Terrace will be closed to through traffic but kept open for buses and taxis.
Trees, shrubs and benches will be installed around the canal, as well as an ampitheatre-style outdoor stage.
The council wants to make a "vibrant" area and reduce the risk of flooding, and has received funding from the Welsh Government and the City Deal for the Cardiff Capital Region.
Changes to the transport network in the area also form part of the project, with a new cycle lane on Station Terrace, wider pavements and better pedestrian crossings around Queen Street train station, and an improved junction between Adam Street and Churchill Way.
Councillor Michael Michael, cabinet member for clean streets, environment and recycling, said: "The opening of the dock feeder canal and the new transport scheme marks the beginning of a new district centre for the city, acts as a catalyst for new investment, and plays an essential role in managing traffic flow and surface water drainage in the city centre.
"A series of rain gardens will be built, with specific soil and planting to treat the surface water, to remove pollutants before the water flows into the canal. This will ensure that 3,700 square metres of water will be diverted from the sewage system each year, reducing the cost and energy of treating this water through the sewage pumping station at Cardiff Bay."
Long term aims for the Canal Quarter cover the east part of the city centre, including down to the Motorpoint Arena, the lanes behind St David's shopping centre, and Guildford Crescent.
The arena could be knocked down, while new apartments, hotels, shops and offices could be built in the area. The council is hoping the project will create new job opportunities.
The works won't affect access to businesses on Churchill Way, but the taxi rank will be moved to North Edward Street where new charging points will be installed for electric taxis.