March 17th marks that time of the year when the Irish can really demonstrate their true colours and celebrate St Patrick's Day in style, more than likely with a pint or two of the 'black stuff' and plenty of oversized hats on their heads, as Ireland's national holiday gets into full swing. In recent years though, another tradition seems to have become a part of the accepted celebrations, as the 'Global Greening' concept has arisen and expanded since 2010, when it began on a far smaller scale. Tonight it is expected that at least 150 landmarks across the globe will be illuminated with green light to add their own personal contribution to the event.

'Global Greening' is an initiative devised by Tourism Ireland, which encourages the world to unite with their country for one day and help to throw the spotlight on Ireland, by lighting up their iconic structures with green light. From its small beginnings in 2010, when 'just' the Sydney Opera House participated, it has expanded year on year to become the truly global event it is today.

Some of the landmarks involved have already switched their green lights on in advance of the day itself, including Rio de Janeiro's iconic Christ the Redeemer Statue and Nelson's Column in London to name but two. Expected to follow suit are such diverse landmarks as Rome's Colosseum, the Empire State Building, Disneyland Paris' Sleeping Beauty Castle, the Niagara Falls, the 'Welcome' sign in Las Vegas and even the Great Wall of China, perhaps opening up the possibility of a 'twinkle' of green even being observed from space.

New structures and countries seem to be added each year, with 2015 'welcoming' Edinburgh Castle, Nashville's Grand Ole Opry, the Sacré Cœur basilica in Paris and even the Equator Sign and Line in Uganda - all are to go green to Show their support.

Ireland hope that by utilising such global publicity, they will be able to promote the country in a unique manner, attracting both the business sector and people to come to their country for holidays in the future.

Estimations based on last year's efforts suggest that they captured 5 million euros worth of new business, with high hopes for an improvement on that this year.

Ireland have big plans indeed, with Tourism Ireland putting plans in place to spend some 21.5 million euros on promoting what the island has to offer in the first two quarters of 2015.

The #GoGreen4PatricksDay initiative seeks to make it clear that there is a link between St Patrick's Day, the Global Greening events and Irish holidays.

Part of their initiative involved last week's screening of a video featuring narration by the Irish film star Liam Neeson, with the message "every day is bathed in green" used to hopefully draw visitors to the Emerald Isle.

Whatever the motivation behind the global 'green' event, expect plenty of selfies to be taken as revellers around the world take advantage of the novel backdrops available, to grab themselves a slightly unusual picture for their social media albums.