Complex sentence: Later, when the nearby A345 was improved and routed through Durrington Walls in 1967, two timber circles were discovered within the henge along with vast amounts of animal bones and associated Neolithic pottery and tools.
Split into simpler sentences: Later, when the nearby A345 was improved and routed through Durrington Walls in 1967, two timber circles were discovered within the henge. Also discovered were vast amounts of animal bones and associated Neolithic pottery and tools.