This popular celebration of our built heritage, organised by the Northern Ireland Environment Agency (NIEA), is your chance to see inside many buildings that aren't usually open to the public.
Over 310 buildings and special events such as walking tours, boat trips and historical re-enactments are taking place across Northern Ireland - all free of charge.
Commenting on the wonder and beauty of our historic environment Environment Minister, Alex Attwood said: "The rich diversity of our built heritage is illustrated in the vast range of buildings opening their doors over the weekend from the White House in Newtownabbey built over 400 years ago, to the new Giant's Causeway Visitor Centre, there is something for everyone.
"Visitors to County Fermanagh will for the first time be able to visit Devenish Parish Church, St Molaise and see inside a number of Fermanagh's other spectacular buildings and homes such as Headhunters Railway Museum, Tully Castle, Monea Castle, Belle Isle Estate Courtyard and Coach House, Castle Coole, Devenish Island, Florence Court, Crom and one of Northern Ireland's most important and the historic stately homes Colebrooke Estate.
"This is the fifthteenth year that EHOD has taken place in Northern Ireland and it has become the largest built heritage cultural event in Northern Ireland with over 58,000 people taking part last year. It provides an opportunity to see behind the facades of some of our historic buildings that would not normally be open to the public and also illustrates the importance that built heritage has in our daily lives."
The Minister added: "EHOD gets better and better every year with more buildings and events. This year we are celebrating the launch of the Titanic and marking the 100th anniversary of her tragic demise with a maritime theme. Visitors can enjoy a Titanic photography walking tour, Magilligan Martello Tower, Belfast Harbour Commissioners Office or a walking tour of Donaghadee.
"The scale, wonder and beauty of our historic environment here is unsurpassed on any part of these islands. I believe protecting and promoting our heritage can be done successfully and sustainably. The built and natural heritage will be the biggest part of future increases in tourist numbers and spend. Six of the ten top visitor attractions are our built and natural heritage. Growing tourism from a £500 million to a 31 billion a year industry will revolve around the positive protection and development of this heritage."
Concluding Minister Attwood added: "I extend a big thank you to all the building owners, volunteers and the whole host of people who arrange activities. Without them, these open days would not be possible."
Log on to www.discovernorthernireland.com/ehod to find out more about the properties opening near you.