amphitheatrical

amfiteatterimainen Having some of the characteristics of an amphitheatre.
1829, "Metropolitan Improvements", in The Mirror of Literature, Amusement, and Instruction, Vol. 13, No. 361, page 184http://www.gutenberg.org/etext/13578:

A new Chapel, of novel design, being of an amphitheatrical form, has been recently completed, from the designs of W. Brooks, architect.