Lincoln police and council officers have told a group of travellers to leave after they set up camp on The Lawn.
The “unauthorised encampment” was photographed by a resident who described it as a “horde of caravans” on the site on Saturday.
A spokesman for the council said they were aware of the issue.
Becky Scott, Legal and Democratic Services Manager at City of Lincoln Council, said: “Alongside Lincolnshire Police, we have visited the site this morning (Monday) and a letter requesting they vacate the site immediately has been issued.
“We will continue to work with police to deal with this matter under the Unauthorised Encampment Protocol between us and Lincolnshire County Council.”