Ordnance Survey Ireland (OSI; ) is the
national mapping agency of
Ireland. It was established in 2002 as a body corporate. It is the successor to the former Ordnance Survey of Ireland. It and the
Ordnance Survey of Northern Ireland (OSNI) are the ultimate successors to the Irish operations of the British
Ordnance Survey. OSI is part of the
Irish public service. OSI has made modern and historic maps of the state free to view on its website. OSI is headquartered at Mountjoy House in the
Phoenix Park in Dublin. Mountjoy House was also the headquarters, until 1922, of the Irish section of the British Ordnance Survey.