(and some adjacent buildings)
Less well known than its neighbours at Ely and Norwich, it contains one of the most spectacular ( and slightly larger) displays of the Romanesque period of abbey churches, having nave, chancel and transepts of C12th origin with little later alteration.
It is also almost 2 cathedrals, the earlier one being encased in a later of C14th & C15th. This arrangement makes for an extraordinary degree of 3 dimensional form around the perimeter.

Brief history at ( http://www.sacred-destinations.com/england/peterborough-cathedral
For fuller information see ( http://penelope.uchicago.edu/Thayer/E/Gazetteer/Places/Europe/Great_Britain/England/_Topics/churches/_Texts/KINCAT*/Peterborough/1.html