cirque

noun3

1. •
   A curved depression or natural amphitheatre, especially one in a mountainside at the end of a valley.

   • Whose savage trample thus could pad the dank / Soil to a plash? toads in a poisoned tank, / Or wild cats in a red-hot iron cage— / The fight must so have seemed in that fell cirque. — 1855
2. •
   (historical) A Roman circus.

   • Nero exhibited these Spectacles in his own Gardens, impiously joining to them the Diversions of the Cirque, and appearing himself publicly in the Habit of a Charioteer, sitting in his Chariot[…]. — 1722
3. •
   (literary, old-fashioned) Something in the shape of a circle or ring.