The remains of the only known Roman chariot racing track in Britain will be on show on Saturday.
Chariot racing was very popular in the Roman world
The track - which is thought to be 2,000 years old - was discovered by builders under the former Calvary barracks in Colchester, Essex.
It is thought the arena could have provided seating for 8,000 people.
New homes are being built on the 209-acre site but developers Taylor Woodrow have said they plan to include the find into the project.
The tour could be the only opportunity for the public to view the site before it is covered up for preservation.