St Mary's Cathedral

Most people walk past St Mary's Cathedral and think nice church, keep moving. That is a mistake. Because beneath your feet, in the crypt, is one of the finest mosaic floors in the world, and almost nobody goes down to see it.

The mosaic is a Celtic cross forty-two metres long and twenty-one metres wide, inspired by the illuminated manuscripts of the Book of Kells. It was created by the Melocco Brothers in nineteen thirty-four, and its intricacy is staggering -- thousands of tiny tiles forming interlocking patterns that look like they belong in an ancient Irish monastery, not under a Sydney church. The crypt also holds the remains of the deceased Archbishops of Sydney, including Cardinal Moran and Archbishop Polding, so you are walking over both extraordinary art and dead clergy.

Above ground, the cathedral has its own strange timeline. The original church on this site was destroyed by fire in eighteen sixty-five. The replacement you see now was designed in a gothic revival style and took decades to build -- but the south spires were not completed until the year two thousand. Over a hundred years after construction began, they finally finished the towers. The design always included them. They just ran out of money.

The sandstone was quarried from Pyrmont, the same source used for much of colonial Sydney. On a sunny afternoon, the stone glows a warm golden colour that makes the whole building look like it is lit from inside. Stand on the eastern side of Hyde Park and look back at the facade. The twin spires are seventy-five metres tall and look like they have been here forever, but they are younger than most people reading this.

Go downstairs. See the mosaic. It is free, it is breathtaking, and the crypt is almost always empty.