The open/closed dichotomy is even more marked at the Ussher Library down the street, by McCullough and Mulvin with Keane Murphy Duff. Although this is only the second building to cut an entrance through Trinity’s northern perimeter defences along Nassau Street (the first being Ahrends Burton and Koralek’s arts building further west), this gesture at accessibility is belied by the face that the building presents to the street. Or rather, chooses not to present. You are looking at one end of the building, which is set sideways to the street and divided into three parts at this point. You get three angled, granite-clad elevations that are almost totally blank apart from (as with the Millennium Wing) a few arrow-slit windows. This too is a bastion, an image reinforced by the ticket booth slotted into the corner for people arriving to see the college’s principal treasure, the Book of Kells. No welcoming portal this. It is a Shakespearian porter’s lodge, worthy of Macbeth.

Architect Valerie Mulvin declares herself particularly satisfied with this elevation, pointing out that the windows and tall strips of granite cladding (in three widths) speak of the volumes of books contained within. I think that the angled masses of the building play a game with the various conflicting grid-patterns present in the city at this point, but if so, the upshot is something seemingly random, haphazard. The building gives you the cold shoulder.

But then, all you have to do is wander eastwards, back towards the National Gallery’s Millennium Wing, and the rationale of the James Ussher libary becomes clear. It presents a very open face indeed across Trinity’s sports field, which with its cricket pitch and pavilion is a miraculous survival from another age, an astonishing thing to find in a city centre.

Where Benson and Forsyth’s building at the National Gallery is a complex piece of urban intervention and spatial gymnastics, threading its way past and partly absorbing a retained 18th century building, the library is a simpler affair. Essentially it is a slightly wedge-shaped atrium building, given some articulation by a separately-expressed conservation lab at the rear, and a stepped lantern roof profile. Looking east as it does allows for an extensively glazed façade, the big glass panels augmented at the ends by panels of stainless steel mesh. These conceal opening interior ventilation slots, demanded by the librarians. Architects are always optimistic when it comes to stainless steel - they persist in naively believing that it really is stainless, which is true only of the most expensive, kitchen-grade variety. Of course the mesh panels here are staining, and some may be replaced.