Complex sentence: Baynard's Castle was at various times a castle, house and palace that existed on the same site, in the south west corner of the City of London, for 600 years from the time of the Norman Conquest until the Great Fire of London.
Split into simpler sentences: Baynard's Castle in London was at various times a castle, house and palace. It existed on the same site, in the south west corner of the City of London, for 600 years from the time of the Norman Conquest until the Great Fire of London.