Get me to the church on time!

The roundabout at the bottom of Macquarie Street north. I am standing close to the security booth at the entrance to the Opera House. On the right is the collection of swanky apartments collectively known - by riff-raff like me - as the "toaster". On the left is the quarry wall from which much of the sandstone was hewn in 1838 by George Barney and his convict-gang, to construct "semi-circular quay". Atop the sheer sandstone face sits a railing that marks the edge of the Tarpeian Way, between Macquarie Street and Government House in The Domain. Is this a Cadillac?