Landmarks across the world were lit up blue to celebrate the birth of the royal baby last night (22.07.13).

The UK, Canada, Australia and New Zealand joined in celebrating the birth of Prince William and Duchess Catherine's baby boy, lighting up their most iconic buildings in red white and blue - the colours of the UK flag - or regal shades of blue, signifying the arrival of a boy.

In London - where the news Duchess Catherine had safely delivered her baby was released at 20.30pm GMT - Tower Bridge was lit in blue lights, while the waterfalls in Trafalgar Square were also coloured blue. The London Eye opted for red, white and blue, while the BT Tower broadcast a message reading ''It's a boy''.

London Mayor Boris Johnson said: ''Huge congratulations to the Duke and Duchess on the birth of their first child who will, by virtue of being born in this great city, be a Londoner through and through.

''I am sure millions of Londoners will be raising a glass today to toast this wonderful news.''

Also in the UK, the Blackpool tower glowed in blue, as did Niagara Falls, 3,300 miles away on the border between the US and Canada. Also in North America, Toronto's CN Tower and the Peace Tower were lit for the Prince of Cambridge. Australian city Brisbane also bathed its Story Bridge in blue light as a tribute.

Over in New Zealand 37 separate landmarks were lit in blue for the baby, including Auckland's Sky Tower and Cloud building, Christchurch Airport, Dunedin Town Hall and a sheep dog-shaped visitor centre in Tirau.

Prime Minister John Key has also offered his congratulations to the popular young couple, saying: ''I know they will make excellent parents''.

He also showed off New Zealand's gift to the pair, a hand-spun, hand-knitted fine lace shawl, similar to one presented to Prince William when he was born.