Dublin is small. About 590,000 people live in the city proper and around 1.5 million in the wider area — roughly a quarter of the population of the Republic. The historic centre is walkable end to end in half an hour.
That smallness is the first thing to understand, because it makes Dublin feel less like a capital than like a large town that acquired national institutions.
The shape of it
The Liffey runs west to east through the middle and divides the city into northside and southside, a distinction Dubliners take more seriously than the geography warrants. The southside has historically been wealthier and carries most of the Georgian architecture; the northside has O’Connell Street, the GPO and a chip on its shoulder about the whole business.
Two canals — the Grand to the south and the Royal to the north — loop around the centre and are the informal boundary of the inner city. Almost everything a visitor wants is inside them.
Postcodes are a usable shorthand and Dubliners use them constantly. Odd numbers are north of the river, even numbers south. Dublin 1 is around O’Connell Street, Dublin 2 is the Grafton Street and government quarter, Dublin 4 is the affluent southeast, Dublin 7 and 8 are the near northwest and southwest.
Dublin Bay curves round the east, with Howth Head at the north end and Dún Laoghaire and Killiney at the south, and the Wicklow Mountains rise immediately south of the city — visible from many streets, and the reason you can be on a mountain within forty minutes.
The name
Dubh Linn, the black pool, was a Viking harbour on the Poddle, a river now culverted and running under Dublin Castle. The Irish name in use today is different: Baile Átha Cliath, the town of the hurdled ford, which is what appears on the buses and the road signs.
Two names for two settlements that merged, and the older one survives in English while the newer one survives in Irish.
Language
English is the everyday language of the city. Irish is the first official language of the state, compulsory in schools, and used natively by a small minority mostly outside Dublin. You will see it on every road sign, on the buses and on official buildings, and you will rarely hear it.
Hiberno-English has its own grammar — “I’m after eating” for the recent past, “will I?” for “shall I?” — and a Dublin accent that varies sharply by a few streets.
The climate
Mild, wet, and changeable rather than extreme. Winters rarely go below freezing, summers rarely above 22°C, and snow is unusual.
Rain is the constant, and it is mostly light and frequent rather than heavy — around 130 days a year with measurable rainfall, but a lower annual total than many people assume. It clears fast. Nobody carries an umbrella; everyone owns a hood.
Daylight swings hard: about seventeen hours in June, and dark by four in the afternoon in December.
How it got here
Viking longphort from around 841, Norman town from 1170, and the seat of English administration in Ireland for seven centuries. It boomed in the eighteenth century — the Georgian squares, the parliament, the Custom House — and then the Act of Union in 1801 removed the parliament and the money left with it.
The nineteenth century was decline and some of the worst slums in Europe. Independence in 1922 made it a capital again, of a poor and emigrating country, and it stayed poor until the 1990s.
The Celtic Tiger from the mid-1990s changed the city faster than anything since the Georgians, and the 2008 crash reversed a good deal of it. What you see now — the tech offices in the Docklands, the cranes, the housing crisis, the young population — is the result of both.
Practical shape
Everything is walkable. Two tram lines, a coastal railway and buses fill the gaps — see getting around.
It is expensive, particularly for accommodation and drink, and the best museums are free.
It is young. A third of the population is under thirty, and the city’s food, music and nightlife have changed accordingly in the last decade.