Complex sentence: The original hall was built in the 10th century by the Gresley Family (Nigel Gresley (1876-1941), being famous for the Sir Nigel Gresley and Mallard locomotives).
Split into simpler sentences: The original hall was built in the 10th century. Built by the Gresley Family (Nigel Gresley (1876-1941), being famous for the Sir Nigel Gresley and Mallard locomotives).