Complex sentence: A'secret tunnel' exists at Pevensey Castle in East Sussex, although not open for public access-it links the keep with the former market square and is thought to be Norman in origin, although was reused during WWII.
Split into simpler sentences: A'secret tunnel' exists at Pevensey Castle in East Sussex, although not open for public access. It links the keep with the former market square and is thought to be Norman in origin; it was reused during WWII.