There is only one colour in fashion on this day. St Patrick’s celebrations sees the wearing of the green from the streets of Ireland to far flung destinations around the globe.

With the Washington Monument in the background, birds fly over a fountain whose water has been dyed green for St. Patrick's Day, Tuesday, March 17, 2015, on the South Lawn of the White House in Washington.

With the Washington Monument in the background, birds fly over a fountain whose water has been dyed green for St. Patrick’s Day, Tuesday, March 17, 2015, on the South Lawn of the White House in Washington. Image by (AP Photo/Jacquelyn Martin)

Even the fountain on the South Lawn of the White House in Washington DC was today sprouting emerald green water in honour of the occasion.

Edinburgh Castle in Scotland illuminated green as it is among more than 100 international landmarks turning green to mark St Patrick's Day.

Edinburgh Castle in Scotland illuminated green as it is among more than 150 international landmarks turning green to mark St Patrick’s Day. Image by Gareth Easton/PA Wire

This year more than 150 buildings worldwide went green as part of a Tourism Ireland initiative. They include the Colosseum in Rome, the Sacré Cœur basilica in Paris, the Great Wall of China, Nashville’s grand Old Opry and Edinburgh Castle in Scotland.

The Sydney Opera House goes green for St Patrick's Day.

The Sydney Opera House goes green for St Patrick’s Day. Image by Jean-Pierre Bratanoff-Firgoff

London’s Eye, the Leaning Tower of Pisa, the Redeemer statue in Rio de Janerio and Niagara Falls have already shone the green torch in previous years and are doing it again.

Disneyland Paris goes green for St Patrick's Day.

Disneyland Paris goes green for St Patrick’s Day. Image by Sylvain CAMBON

Meanwhile, up to two million people are expected to line the streets of New York today as the city goes green in celebration of St Patrick’s Day.

St Patrick's Day Parade in New York city

St Patrick’s Day Parade in New York city Image by MarineCorps NewYork / CC BY 2.0

The parade will include bands and groups from Ireland who have travelled to the Big Apple as well as local bands, dancers and marchers from around the USA. The main route for the spectacular will be up Fifth Ave. to 79th St.

The water in the fountain on the South Lawn of the White House in Washington, is dyed green for St. Patrick's Day.

The water in the fountain on the South Lawn of the White House in Washington, is dyed green for St. Patrick’s Day. Image by (AP Photo/Jacquelyn Martin)

An openly gay group will march under a banner in the parade for the first time. However Mayor Bill de Blasio has said he will stay away as the inclusion of NBC Universal’s contingent is not sufficiently adequate for him to attend.

He accepted that having one gay group was “progress” but he claimed the parade was confined to people who work for NBC where the group is from.

The New York Daily News said that De Blasio used the parade in Boston as an example where a parade was open to the LGBT community.