The Thornleigh zigzag railway originally ran from the main rail line near Thornleigh to a historic quarry, near present day De Saxe Cl, Thornleigh. There are only minor fragments still visible today. The 'Heritage Trail' in Thornleigh has interpretive signs for the railway and the old Thornleigh Quarry. A book is available with some detail on railway and associated quarry: 'Sydney's Forgotten Quarry Railways' by John Oakes, ISBN 0 9757870 3 9