After more than 100 years in the making, St John's Anglican Cathedral in Brisbane, Australia has finally been completed.

The last medieval constructive project of its kind in the world, St John was completed with the lowering of a 43 feet tall copper-clad spire onto the Central Tower, reports the Anglican Church.

"This represents practical completion of the project more than 102 years after it began and 119 years after it was first designed by English Victorian gothic architect John Pearson," said the Archbishop of Brisbane, Dr Phillip Aspinall, who blessed the spire during a ceremony on Tuesday.

The spire sits on top of the tower that houses the cathedral bells.

"Up to 100,000 stones have been used for the complete cathedral construction project which has involved hundreds of people across generations," he added.

The gothic cathedral was designed in 1889 and construction began 17 years later. It was built in three phases starting in 1906, and with the final stage taking place in 1989. The cost of the final stage alone was $39.5 million.

"This cathedral is a beautiful and sacred building but it is nothing without people. I thank all supporters of the project and invite all Queenslanders to visit and share in the experience that is St John's," said Archbishop Aspinall.

An official ceremony to mark the completion of St John's Cathedral is scheduled next year during the Anglican Diocese of Brisbane's 150th anniversary celebration.