IRELAND’S LARGEST TREE HOUSE & ADVENTURE PLAYGROUND OPENS AT BIRR CASTLE Minister for Children Officially Open New Visitor Attraction to mark National Recreation Week. Standing 39 feet tall (as tall as a three storey building), Ireland's largest Tree House, the centrepiece for a new adventure playground at Birr Castle Demesne, Co. Offaly was officially opened.Marking the start of National Recreation Week, Minister for Children, Frances Fitzgerald T.D. officially opened the new visitor attraction, one of Europe's largest public tree houses.Photo Chris Bellew  Copyright 2013 Fennell Photography