Access to most heritage sites managed by the Office of Public Works (OPW) is free today and on the first Wednesday of every month for the rest of the year.
The move is designed to encourage more national and international visitors to sites such as the Rock of Cashel, Clonmacnoise and the State Apartments in Dublin Castle. All sites managed by the agency will be free with the exception of Muckross House and Gardens and Muckross Traditional Farms and Glenveagh Castle.
The OPW is responsible for the maintenance and management of over 750 national monuments around the country.
The decision to grant free access was made by the Minister of State responsible for the OPW, Brian Hayes, who said it was done to stimulate interest in the built heritage of the country.
The scheme will last until the end of the year when its success or otherwise will be reviewed.