Complex sentence: In 1555 the then owner, Francis Hastings, 2nd Earl of Huntingdon, pulled down much of the fortified house and replaced it with a large Tudor brick house, with numerous chimneys and gables.
Split into simpler sentences: In 1555 the then-owner, Francis Hastings, 2nd Earl of Huntingdon, pulled down much of the existing fortified house. He replaced it with a large Tudor brick house, with numerous chimneys and gables.