St Patrick's Day, though mostly an American holiday, always conjures up images of green beer, leprechauns, and four leaf clovers. What better time of year to celebrate your (or someone else's) Celtic heritage than spring time? There are plenty of options to choose from - in the US, Ireland, and throughout the UK by visiting Yorkshire or going in search of King Arthur's legacy.

Ireland - The cradle of Celtic civilization is high on many must-do lists. In 2013, Ireland will be hosting The Gathering, a year-long event to encourage people of Irish descent to come visit, explore their culture, and maybe learn a thing or two. There are many opportunities to do just that on Viator. Trips to the Blarney Stone, the Wicklow Mountains, the Cliffs of Moher, Newgrange, and more offer the sweeping visits and rich history. For those interested in carousing in Dublin, a tour of the Guinness Storehouse, a musical pub crawl (or a literary one), an Irish house party and some dancing may be in order. Or combine the best of everything with an amazing 8-Day tour through Ireland. Just don't forget to wear green!

Boston - the epicenter of Celtic and Irish culture in the US, Boston has a superlative historical pub crawl. Get your fix for history and quench your thirst in one tour!

New York - There is no denying that NYC has a lot to offer. Celebrate your greenest day of the year with a pub crawl, a craft beer crawl, a nightclub tour, or go behind the scenes of the Brooklyn Brewery or a distillery, and enjoy one of life's simplest pleasures. For the more culturally minded, the Broadway show "Once" is a love story revolving around music and set in Dublin.