Complex sentence: Most traces of the 17th-century house were obscured when it was rebuilt and given a classical facade around 1800, when it was owned by Robert Bush, who's father had been a successful Bristol pewterer.
Split into simpler sentences: Most traces of the 17th-century house were obscured when it was rebuilt and given a classical facade in about 1800. It was then owned by Robert Bush, whose father had been a successful Bristol pewterer.