The Commonwealth of Australia Constitution Act (UK) was passed on 5 July 1900 and given Royal Assent by Queen Victoria on 9 July 1900. It was proclaimed on 1 January 1901 in Centennial Park, Sydney.

Where was the official Federation ceremony held?

When the Commonwealth of Australia was declared on 1 January 1901, a ceremony was held in Centennial Park in Sydney.

When was Federation declared in Australia?

Australia becomes a nation on 1 January 1901 when the six colonies federate, and the Commonwealth of Australia is proclaimed in Centennial Park, Sydney.