The Irish pub is essentially a product of the nineteenth century, as that was when the greater part of our common urban building was erected, replacing earlier thatched houses and so on. Also there was the practice of awarding licences to general traders, grocers, etc., so that one finds the curious dual trading of shop-in-front - hardware etc., and pub behind. Later in the century with the great programme of Catholic church-building, landlords could fit out the interiors with richly-carved wooden bars, church tiling on the floors, and so on. Etched glass and brass fixtures are to be found in the better ones, but many remain very simple, with t-and-g boarding, a few barrels mounted over the rear counter, and sometimes ornate gas-lamps in the windows. One overlooked feature is thatinstead of signs, pubs were painted in a particular livery, which never changed - in an age of illiteracy, one had to be able to identify the pub through say its being red-and-black. Ofcourse names were used, but generally the family name of the licensee, and sometimes done in gold, covered by glass.
One could not see into the pub directly - an important consideration securing the privacy of the pub. Thus the front windows tended to have a high sill, and a great single pane over ( 19 c. plate glass). The snug, a small compartment between front window and the bar service area, or elsewhere in the building, was for the reception of ladies, who may have been forced to settle sales of farmstock in private with the ritual drink and 'luck-penny' exchange. The cities boast saloons on the international style of 'parlour houses', with very ornate design, stained glass and carving, the rural ones can be very informal, with drinking taking place in the business end, giving rise to the range of drawers that are installed in English theme-pubs.
It is hard to write a history as there is such variation, but a number of pre-eminent examples can be easily idfentified in any area - in N. I. some of the good ones are listed - some of the good-but-simple ones are going fast. As regards the imagery, there were of course no medieval ones, so huge timber beams are never found, or other features of English pubs that have now become common worldwide. Therefore desite a lot of variety, the Irish pub has a recognisable gamut of features which give it its quintessential character, and surely it is this identity that has swept the Continent, where the examples are far less 'commercial' than the ones found everywhere now in England, with prissy names - products of interior designers who usually get things mixed up a bit, and the whole effect becomes coy in the extreme.
The above contribution is the result of many happy hours of self-financed research around the world!