Managers at a Rotherham nature park have said they were sickened after thieves stole more parts from a sculpture at the site.
Police were contacted after one of the crossbeams was taken from the Steel Henge structure at the Centenary Riverside park on Wednesday.
When staff went back on Friday, thieves had broken through the padlocks and taken one of the crosspieces.
The sculpture comprises a circle of metal plinths and beams.
These were excavated when the park was created.
Hannah Wittram, of the Sheffield and Rotherham Wildlife Trust, which manages the park, said: "One of the crosspieces has been taken which is very sickening and frustrating.
"We've got a security bollard going into the car park which the thieves have managed to damage and drive into the car park."
"Obviously we're going to have to raise money if we want to replace the stolen pieces. We're discussing what to do about it now."
Centenary Riverside Nature Park is a joint venture between Rotherham Metropolitan Borough Council and the Wildlife Trust for Sheffield and Rotherham.
It forms part of the £2bn Rotherham Renaissance programme to regenerate the town centre and bring the riverfront back into use.