Complex sentence: The site for the Catholic church overlooked a barren area upon which the bricks for Macquarie's buildings were made, now Hyde Park, with avenues of trees and the Archibald Fountain.
Split into simpler sentences: The site for the Catholic church overlooked a barren area upon which the bricks for Macquarie's buildings were made. The area is now Hyde Park, with avenues of trees and the Archibald Fountain.