St. Mary's Cathedral is the site of the Archbishop of Sydney. It was built on the site of Sydney's first Catholic Church. It is the largest and oldest religious building in Australia. Just opposite Hyde Park, the cathedral is built of sandstone. The Gothic style is the architectural legacy of medieval cathedrals in Europe. It was founded in 1821, and the Catholic priest officially came to Australia in 1820, so St. Mary's Cathedral is also known as the mother of the Australian Catholic Church. The inside of the church can be visited freely and photographed. It's not open on Monday.