Complex sentence: Runnymede is a water-meadow alongside the River Thames in the county of Surrey, England, associated with the signing of the Magna Carta and today the site of a collection of memorials.
Split into simpler sentences: Runnymede is a water-meadow alongside the River Thames in the English county of Surrey. It is notable for its association with the signing of the Magna Carta, and as a consequence is the site of a collection of memorials.