The chancel of the old Holy Rood church - it has featured on this blog many times. It was Swindon's original parish church and is first mentioned in documents dating from 1154. It was rebuilt about 1300 but fell into disrepair after the new Christ Church was built. Partly demolished in 1852, leaving only the chancel and a few arches (perhaps this is where the ammonite stone came from) English Heritage has scheduled the remains of the church as an ancient monument.
There is a concentration of yews in this part of the Lawns, not least in the churchyard, which is not accessible to the public. The one in the far corner of the churchyard looks very ancient indeed.