One day is plenty to get the measure of Derry, because almost everything worth seeing sits inside, or a short stroll from, the old walled city. The whole walled centre is barely half a mile across, and the river, the Bogside and the newer quarter across the water are all within an easy walk. Here is the day we would give a friend arriving off the morning train, timings and all. Treat the clock as a guide rather than a rule.
Morning: the walls and the Guildhall
Start in Guildhall Square around 9am. Grab a coffee, get your bearings, and look up at the Guildhall itself before you climb anything. Then head up onto the city walls, the only complete circuit of walls left in Ireland and among the best preserved in Europe.
Walking the full circuit is about a mile and takes most people an hour to ninety minutes at a browsing pace, longer if you stop at every bastion and cannon, which you should. From up top you get the lie of the land in a way no map manages: the Bogside and its murals on one side, the river and the Guildhall on the other, seven gates and four hundred years of history laid out beneath you. Watch your footing after rain, the surface can be slick, and there are a few short flights of steps.
Come down for the Guildhall itself, which is free to go into and worth twenty minutes for the stained glass alone. Verify Guildhall opening hours and whether entry is free on the day you visit. There is usually an exhibition on the ground floor and a small café if you need a second coffee.
Late morning: down into the Bogside
From Guildhall Square it is about a ten-minute walk, mostly downhill, to Free Derry Corner and the Bogside. This is flat, easy ground, and it is where the city's civil-rights history lives.
Give yourself an hour here. Stand at Free Derry Corner, walk the length of the People's Gallery, the run of large gable-wall murals by the Bogside Artists on Rossville Street, and take in the Bloody Sunday memorial. The Museum of Free Derry tells the story in more depth if you have time and want it. Verify Museum of Free Derry opening hours and admission price. It is a serious part of the city and rewards a slow, quiet visit.
Lunch
By now it is around 1pm and you have earned a sit-down. Walk back up towards the centre and eat in or near the Craft Village, a small courtyard of independent shops and cafés tucked between Shipquay Street and Magazine Street. The city centre around the Diamond has plenty of options too, from quick bites to proper sit-down lunches. Budget an hour.
Afternoon: the Craft Village and across the river
After lunch, wander the Craft Village and the streets inside the walls at a slower pace. If the weather has turned, the Tower Museum near Magazine Gate is a good indoor hour, with a display on the Spanish Armada wreck recovered off the Donegal coast up top. Verify Tower Museum opening hours and admission price.
Around 3.30pm, make for the river and cross the Peace Bridge. The bridge is a curving footbridge that opened in 2011 and links the old city with Ebrington, the regenerated former army barracks on the far bank. The crossing itself takes only about five minutes, but it is one of the nicest short walks in the city, and Ebrington Square is a fine place to stop. The Walled City Brewery here is a good spot for an early pint or an early dinner if you want to eat on this side. Verify Walled City Brewery opening days and hours.
Evening: Waterloo Street
Cross back over as the light goes and head for Waterloo Street, the short, steep lane that is the heart of Derry's nightlife. This is where the music is. Peadar O'Donnell's and the adjoining Gweedore Bar run traditional sessions most nights, and the whole street has a good buzz to it. Verify current live-music nights and start times at Peadar O'Donnell's.
Have your dinner wherever takes your fancy, settle in with a pint, and let the session carry the evening. If one day is all you have, that is a good one.
If you have a weekend
With a second day, get out of the city and see the coast and the country around it. Two easy options, both within reach for a day trip:
The Giant's Causeway. Head east along the Causeway Coastal Route, one of the great drives, taking in Downhill, Mussenden Temple and the beaches along the way. The Causeway itself, with its columns of basalt, is roughly an hour to an hour and a quarter by car from Derry. Verify current drive time and Giant's Causeway visitor-centre parking and admission arrangements. Give the whole outing most of a day if you stop along the coast.
Inishowen. Or cross into County Donegal and the Inishowen peninsula, in the Republic of Ireland. You will not notice much of a border beyond a change of road signs and prices in euro rather than pounds. The Grianán of Aileach, an ancient stone ring fort on a hilltop with enormous views, is only twenty minutes or so out of the city. Verify drive time to Grianán of Aileach. Push on and you can reach Malin Head, the most northerly point on the island of Ireland, and a string of quiet beaches on the way.
Either way, you come back to Derry for your second night, and Waterloo Street will still be there.