In the grounds of Downpatrick Cathedral, a large stone slab marks the grave of three saints, St Colomb, St Bridget and St Patrick, who were responsible for converting the pagan Irish to Christianity.

St Patrick's Day in Downpatrick begins with services in the cathedral and a wreath-laying ceremony at the grave of the saints. At 2.30pm the carnival parade sets off, led by a local man dressed as the great saint himself, wearing an oatmeal-coloured toga and carrying a wooden staff. Following the saint come spectacular floats, bands, American and vintage cars. Catholics and Protestants alike march in wild fancy dress. The streets are lined with people wearing plenty of green in honour of the saint. The parade lasts about an hour and finishes below the cathedral.

Downpatrick is believed to originate from St Patrick's first efforts to convert Ireland to Christianity. When St Patrick returned from France in the 432AD, he sailed up Strangford Loch (the name means "violent fjord" and was coined by the Vikings). From there, the saint sailed up the River Cqoile to a place called Saul, where we know he founded a church and converted the local chieftain Dichu. Nearby was the settlement of Downpatrick, where St Patrick settled and was eventually buried.

Visitors can enjoy concerts, take part in ceilidhs, attend lectures on the history of St Patrick, enjoy sporting events including cycle rides, fun runs, guided walks as well as taking coach tours around Down County.