“ Opened in 1818, the General Post Office on O'Connell Street was designed by Francis Johnston and quickly became one of the most inportant Landmarks in the city. in 1916 an Irish republic was proclained from the steps of the GPO by patriot leaders Padraig Pearse and James Connolly, leaders of the Easter Rising. „
I came here on an A2 history trip last year while studying the change in the relationship between Britain and Ireland in the 19th and 20th century. I visited the GPO as part of the Dublin walking tour (something I would highly recommend, the guide is funny, controversial and highly knowledgeable suitable for tourists and students) the GPO itself is massive, steeped in history; you can see the bullet holes where the British fired on the rebels of 1916. Inside, it's beautiful, there's quite a bit to see, I would recommend just having a wander through, and asking someone if you want to find somewhere specific. It's a working post office, and you can send postcards to home from the famed GPO on O'Connell Street! As you walk in, on your right is the 1916 room, with a beautiful copy of the Proclamation of the Provisional Irish Government, read out to the nation on Easter Monday 1916. There is no entry fee.
In terms of things to do and see, I wouldn't say you would need to be there for more than an hour. The walking tour ended at the GPO, and we spent some time there and then went off to get some lunch. There is a subway across the street, and a MacDonalds just up the road. However, for something more 'Irish' or just not fast food the whole area is packed with traditional Irish pubs, cafes and restaurants. If you can, get a full Irish breakfast, it's like the English one but with more food and Irish Soda Bread which you have to try! Be careful of drinking though, apart from anything else, it's expensive, in the centre of Dublin the cheapest you're going to find a pint is about 5 Euros, you can pay up to 7 or 8 in certain places, but if money's not an issue then don't worry!
I would definitely recommend visiting the GPO, steeped in history this place is really a great place to visit if you have an interest and would like to find out more.