Complex sentence: The first Wembley Stadium (formerly known as the Empire Stadium) was a football stadium located in Wembley Park, London, that stood on the site now occupied by the new Wembley Stadium.
Split into simpler sentences: The first Wembley Stadium (formerly known as the Empire Stadium) was a football stadium located in Wembley Park, London. It stood on the site now occupied by its successor, the new Wembley Stadium.