Simplify the following text for a Grade 9 native English-speaking person.
Original: Without the addition of buttresses , bracing arches and iron ties over the succeeding centuries , it would have suffered the fate of spires on later great ecclesiastical buildings ( such as Malmesbury Abbey ) and fallen down ; instead , Salisbury remains the tallest church spire in the UK .
Simplified: Without the later addition of buttresses , bracing arches and iron ties , it would have fallen down , as spires on other great buildings have done . Instead , Salisbury is said to be the tallest surviving pre-1400 spire in the world .