Half a million people, including more than 100 thousand overseas visitors, are expected to attend the St Patrick’s Day parade in Dublin today.

A larger than normal garda presence will be seen especially in the capital to clamp down on anti social behaviour and to help deal with the massive crowds.

Following 18 months of preparation, the parade theme 'Imagine If', looks to the next 100 years with around three thousand Irish and international participants expected to put on a futuristic show.

It all starts at 12pm.

The route for the Dublin St. Patrick's Day Parade is 2.5 kilometres long and leads from Parnell Square down O'Connell Street, over the River Liffey via O'Connell Bridge into Westmoreland Street, past Trinity College at College Green and on to Dame Street. It then turns left at Christchurch Cathedral into Lord Edward Street, Nicholas Street and Patrick Street before finally finishing at St. Patrick's Cathedral.