From Decisions and report of the jury of award, in the section on Koralek’s winning design:
It is placed in relation to the old Library and the Museum Building so that it naturally forms a courtyard between them which opens on to New Square and serves as an entrance court for both the old and new libraries. It also makes possible the development of a future quadrangle either in the Fellows’ Garden or the western end of College Park. As many as possible of the existing trees on the site have been preserved, and the southern part of the site remains available for future expansion.
In the end it was decided to make this new square from Fellows’ Garden, removing the Magnetic Observatory and awarding the contract to design the new Arts Building (and the Lecky Library within it) to ABK. The desire to build the Arts Building was revealed in the Annual Provost’s Report in 1968.
Here we have a plan of Trinity at the time, hand annotated by Koralek to show the series of squares that make up the western part of College, with the new Fellows’ Square to be carved out by the imposition of the Arts and Social Sciences Building to the south (you can see the outline of the proposed Arts Building as dotted lines).
Below we can see the Arts Building under construction viewed from within the New Library, from the series of photos taken by Tony Cains in 1976:
The Arts Building was opened by the President of Ireland, Patrick Hillery, on 11th December 1978. President de Valera had on course opened the Berkeley 11 years before.
That area left open “for future expansion” was to be the site of the Ussher, which was formally opened by the President of Ireland, Mary McAleese, on 11th April 2003. As we’ve spoken of before, that’s when many of the trees that had been deliberately left by Koralek’s design got the chop.