The new Irish Architectural Archive building - including a public gallery - is a valuable resource that should boost the Archive's profile, writes Helen Meany

Visiting the Irish Architectural Archive used to be like being admitted into a fraternity. Around the polished mahogany table at No 63 Merrion Square in Dublin, a handful of people would pursue their scholarly interest in Irish architecture, darting an occasional curious glance toward anyone who wasn't a regular researcher. A move to No 73 gave the Archive a little more scope, but its new home on the east side of Merrion Square finally does justice to its role as a major cultural institution: Ireland's national buildings record.

The doors opened yesterday on the imposing double-fronted 18th-century townhouse, the largest on the square, which has been expertly restored and refurbished over the past year by a team of architects and conservationists from the Office of Public Works (OPW), led by Niall Parsons. The building was made available to the Archive by the State in 1996, when it was vacated by the Irish Patent Office.

Built in the 1790s, its first recorded occupant was Robert La Touche of Harristown, Co Kildare, clearly a man of considerable means. It was subdivided to form two houses with separate entrances in the 1820s, which were eventually bought by the state in 1912 and used as offices by the National Health Insurance Company. The OPW aimed to restore it as closely as possible to its original 18th-century form, removing the dividing wall through the front rooms as well as the second, 19th-century doorcase.

Inside the high-ceilinged reception rooms, the delicate Georgian cornices and decorative mouldings have been restored by the OPW's plasterers. The stone and metalwork, joinery and chimneypieces have been cleaned and replaced, while the walls have been re-painted in period colours. A new glass lift at the rear leads to the basement storage area, where heavy insulation creates a carefully controlled environment and constant temperature for the preservation of manuscripts.

The scale of the new premises means that the Archive can now accommodate many more researchers and visitors, including school students, with a spacious reading room, accessible to the public without charge or introduction.

Elegant spaces for launches and functions overlook the greenery of Merrion Square. Seminar and lecture rooms will be used by architecture students from UCD and Bolton Street. There's an upstairs room for displaying models, including very recent ones from the competition for Dublin's Millennium Bridge and the new Usher Library at Trinity College, as well as meticulous miniature cardboard models made by the architectural historian Maurice Craig. Most significantly, there is a ground floor gallery for exhibiting selected drawings and manuscripts, as well as hosting visiting exhibitions.

This gallery (the Heinz Gallery) was originally housed in London, in the Royal Institute of British Architects' (RIBA) headquarters in Portman Square.

Designed by Alan Irvine, it was the first gallery created specifically for the display of architectural drawings. When the RIBA's lease expired and its drawing collections went to the Victoria and Albert Museum, the Irish Architectural Archive acquired the gallery, which was then dismantled by the OPW and re-built in 45 Merrion Square - a painstaking process reminiscent of the relocation of Francis Bacon's studio to the Hugh Lane Gallery in Dublin.

For the Archive's Director, David Griffin, having a public gallery for the first time is the realisation of a long-held ambition. "It's marvellous that we can now display our collections to a wider audience. We have more than 100,000 architectural drawings here, dating from 1700 to the present, as well as models, engravings, manuscripts, rare books and journals and modern reference books. The Archive constitutes a self-contained history of Irish architecture."

Isn't there something missing, though? A cultural institution without a café? David Griffin assures me there are plans for one in Merrion Square's other architectural centre, at No 8, where the Royal Institute of Architects in Ireland (RIAI) has its headquarters, publishing offices and bookshop. The two organisations work closely together, and the aim is to create a little quarter that will attract people who are interested in the built environment. Plans are afoot, in conjunction with the Arts Council, for an "Architecture Day", to throw buildings open to the public and raise awareness of historical and contemporary building design.

The Archive's opening exhibition, Collection Building, presents a representative selection of materials. Its curator, Colm O'Riordan, has juxtaposed Victorian artefacts, such as a sketchbook of the celebrated Gothic revivalist, Augustus Pugin, with plans and elevations from the 1970s by Sam Stephenson for a plaza for the Fitzwilliam Tennis Club, which was never built.

Drawings of historical interest include the Gorey Union Workhouse from the 1840s, designed for the Poor Law Commission by the prolific English architect George Wilkinson, which were salvaged from the Custom House, having miraculously survived the fire there in the early 1920s. Fine 18th-century drawings, including an elevation for Leinster House, are part of the extensive Guinness Drawings Collection, which was acquired by the Archive in 1996. These sit alongside Michael Scott's shamrock-shaped design for the Irish Pavilion for New York's World Fair in 1938.

"A lot of people don't realise that we hold 20th- and 21st-century material," O'Riordan says. "We're constantly adding to the collection."

As well as collecting, preserving and cataloguing records of all kinds that relate to the architectural heritage of Ireland (including Northern Ireland), the Archive undertakes its own photographic surveys of Irish buildings on an on-going basis and now has more than 750,000 photographs in its collection. A staff of seven works to ensure that these are catalogued and readily accessible. They are also compiling a database on Irish architects, with links to the RIBA and V&A in London. It currently spans the period from 1700 to 1940 and may be consulted by any visitor to the reading room.

The Archive is a registered charity and receives funding from the Department of the Environment and Department of Arts, Sport and Tourism. While some of its materials are donated, it also solicits sponsorship from banks and companies to assist with acquisitions and, since its establishment in 1976, has been quite generously endowed from these sources.

The Archive is an invaluable resource also for social historians - studying the minute books of Dublin's Artisans' Dwellings, for example - or for film and stage designers who need to recreate period buildings, such as the GPO, which was replicated to scale on the film set of Neil Jordan's Michael Collins in Grangegorman.

As well as being intrinsically beautiful, the drawings and models are often consulted by conservationists and are extremely useful as a practical guide for restoration work.

"But we are not a preservation society," David Griffith says. "The information is available to property developers also. We do not get involved in disputes over buildings. We're keen to keep out of controversy."

This objective approach is also evident in the collections themselves, which are not based on evaluations of architectural quality. All kinds of buildings are documented, from public landmarks to three-bedroom semi-Ds in housing estates. "We're not judgemental about what we take in," Griffith says. "We're not editing history."

The Irish Architectural Archive at 45 Merrion Square, Dublin, is open Tuesday-Friday, 10 a.m - 5 p.m. admission free. Tel: 01-6633040.  www.iarc.ie