The first thing a visitor to Belfast's Linen Hall Library notices is the walk up the stone steps, which has been grooved over time by the tread of patrons and pilgrims as they went up in search of a book or a friend. Is it coincidental, I wonder, that in the Linen Hall, the visitor has to ascend to obtain enlightenment?

The second thing one notices is the silence within. The library is situated in the city centre, Donegall Square North, opposite the rank for City Bus. The noise of roaring engines and smell of stale exhaust fumes can be almost overwhelming at times. Once inside the sanctuary of the library doors, sound is suffocated.

Yet it is not the silence of a mausoleum. People work there. There is the sound of not-so-diligent students whispering over opened, if unread, books. And then there are the floor boards, which in places rock and creak like an old sailing boat. The carpet, so old that it must have come from Ali Baba's cave, badly muffles the squealing of tortured wood.

I was drawn to it in the mid-1980s. A student at Queen's University at the time, it offered a welcome alternative to dull (and cold) university stacks and a dreary Students' Union. There was a sense of history about the place that even the most obtuse could not help but notice, and it offered a handy meeting point for earnest would-be writers.

More serious scholars than I use it as an unparalleled research source on the North. Of the 263,000 books held, some 185,400 deal with Irish and local studies. The Northern Ireland Political Collection is a treasure trove of contemporary history, with over 135,000 items from all parties involved in the Troubles.

Originally founded in 1788 by radicals as a reading society and subscription library, the Linen Hall has always been more than a mere repository for books. Its members were proponents of free and universal education; they supported Catholic emancipation and women's rights. One of its librarians, the United Irishman Thomas Russell - "the man from God knows where" - was arrested on the premises in 1796. He was deported, but returned and was subsequently executed.

Post-second World War, the library was a haunt for local artists, including the dramatist Joseph Tomelty, the novelist Sam Hanna Bell and the painter William Conor. Even those not interested in reading knew where to find it - the IRA firebombed it on one occasion.

And now the library is set to face a new millennium. After extensive refurbishment (costing £3.2 million sterling) the old library in Donegall Square has been renovated, and adjoining premises in Fountain Street have been secured and remodelled.

For the current librarian, John Gray, it is the culmination of almost 20 years' work. He joined the library in 1982 and has watched as, slowly but surely, the institution has begun to regroup to meet future challenges. A report commissioned in 1985 drew attention to the lack of space and urged that options for extending the library be explored. Negotiations to obtain neighbouring property carried on over a number of years.

It was only in 1995 that substantial funds from the Heritage Lottery Fund finally became available. The fund gave over £2 million towards the project. In 1996 a new building was secured and the wheels of change began to turn with increasing speed. September 16th will mark the official opening of the new building and the refurbished old library.

Gray's delight is obvious as he offers a guided tour around his expanded kingdom. He speaks with passion about the importance of maintaining the integrity of two listed buildings, while, simultaneously, of making a statement that the work represents "a new world and future, as well as the past".

"We've managed to reflect the different aspects of the library very well in what we've got," he says. "We obviously start with two listed buildings - the main library which was, in 1865, a linen warehouse; and this building [the new library] built as a warehouse. Therefore, obviously, there are period features . . . we've retained that and make the most of it. In a sense that reflects the historical continuity.

"On the other hand, we had a real opportunity with the link building. We could have made the conservative choice . . . but, much as archivists do if there is a hole in the document, you don't try and forge the missing bit, you put in a piece of clean paper to indicate that something new has gone in here. Perhaps, slightly more dramatically, what we wanted to put in here was a statement that this is an open door."

The statement is well-made. The new public entrance on Fountain Street is bright and airy, while inside wood and glass combine to give a sense of modernity that doesn't overpower. The staircase is broad and there is little sense of the claustrophobia of the old one. Lifts have been installed to offer easy access to the disabled and elderly.

As well as extra storage for books, new space has been created for cultural pursuits. One room has the capacity to be divided off for use as a lecture theatre or indeed for films and small dramas. It will mean, says Gray, that the library can now host two events at the same time, thereby enriching its own cultural programme and offering patrons and public more opportunity to participate.

To encourage participation, the library is organising an Open Door programme, a week of 40 events between September 16th and September 24th - readings, talks, films and exhibitions - to attract people to become members and to use its facilities. Seamus Heaney will officially open the programme and library at the head of a human bookworm - children from five Belfast schools will pass him a book and he will have the task of setting this first tome on the shelves.

Another of the main events will be "Images and Reflections", a series of photographs about the North accompanied with text by contemporary writers, among whom are Heaney, Ciaran Carson, Seamus Deane, Jennifer Johnston, Derek Mahon, Gary Mitchell and Cathal O Searcaigh.

Thankfully, it isn't a litany to the past 30 years of troubles. Yes, those images are here: the Enniskillen bombing, street demonstrations, soldiers and paramilitaries. How could they not be? However, the North is more than armed men in berets and balaclavas. Other images tell of other lives - the poverty of Derry and Belfast, a forgotten Shankill, Armagh in apple blossom. Heaney's pastoral Threshing rubs shoulders with images that depict the stark heartbreak of emigration. (Yes, Northerners had to emigrate too.)

John Gray sums up his library as being "not just a building". He's right.

For information on Linen Hall Library events, contact 048 90321707