Most visitors give Strasbourg two or three nights and then move on. That is a reasonable way to see a city and a wasteful way to use one. Look at the map properly and the case reverses. Strasbourg sits on the flat of the Rhine plain, the Vosges rising to the west and the Black Forest to the east, with a German town at the end of one of its own tram lines. Within about twenty minutes you can be in Germany; within roughly an hour and a half, in Switzerland. This is less a destination with an itinerary attached than a hub with other countries hanging off it.
The corollary is that a longer Alsace trip is not really about Strasbourg at all. It is about deciding how many bases you want, whether you need a car, and which of the two mountain ranges you are prepared to give a proper day to. Get those three decisions right and a week here is unusually rich. Get them wrong and you spend a lot of it waiting at village bus stops.
Two railways, two countries, one plain
Start with this. The Rhine plain carries two north–south railways, one on each bank, belonging to two different national networks, and they are not interchangeable.
The French one is Strasbourg's own: south through Sélestat and Colmar to Mulhouse and on to Basel; north-west out of the plain, climbing through Saverne towards Nancy, Metz and Luxembourg. The German one runs down the far bank — Rastatt, Baden-Baden, Offenburg, Freiburg — and does not serve Strasbourg at all. You join it by crossing the river eastwards to Offenburg or Appenweier, which is why Offenburg keeps recurring below: it is the junction for the whole of Baden, with Baden-Baden and Karlsruhe up the line, Freiburg down it, and the Schwarzwaldbahn climbing inland through Triberg into the Black Forest.
Everything on the French side hangs off the Gare de Strasbourg, the 1880s sandstone station wrapped since 2007 in a glass shell that looks like a dropped contact lens and works rather well.
And then there is the tram. Line D runs from the city centre across the Rhine to Kehl in Germany, roughly fifteen to twenty minutes from the middle of town on an ordinary tram ticket. Kehl is not really a destination: a tidy market town with a pedestrianised centre and gardens along the water. Plenty of people ride out to shop, and the tram carries shopping bags in both directions, but cross-border price differences move with tax rates and inflation, so we would not plan a day around them. The crossing itself is the thing, and it is better done on foot or by bike over the Passerelle des Deux Rives, the double-arc footbridge stitching the Jardin des Deux Rives together across the water. Given the choice, we would send a first-time visitor over that bridge before sending them into any museum.
The train spokes that actually work
Colmar, about thirty minutes south, is the one to take if you take only one. Go for the Musée Unterlinden and Grünewald's Isenheim Altarpiece — a genuinely upsetting object that repays a slow hour rather than a quick lap — then the canal quarter known as La Petite Venise and, if you have the interest, the Musée Bartholdi in the house where the sculptor of the Statue of Liberty was born. Colmar is also the road-and-bus head for the southern wine villages, which matters later.
Sélestat, about twenty minutes out, is the one we would add. Its humanist library is built around the working collection of the Renaissance scholar Beatus Rhenanus: not a treasury of showpieces but a sixteenth-century reader's own shelves, kept together. Sélestat is also the usual railhead for Haut-Koenigsbourg, the mountain castle above Orschwiller rebuilt on a grand scale for Kaiser Wilhelm II before the First World War. A seasonal shuttle bus generally links station and castle; confirm the current timetable before you plan a day around it, because outside the main season it thins out or disappears.
Mulhouse, roughly fifty minutes to an hour away, is not a beautiful town and we would give it a day regardless, for two very large industrial museums: the Cité de l'Automobile, built on the Schlumpf brothers' privately assembled collection of Bugattis, and the Cité du Train. Each will take half a day if you care at all. Nearby at Ungersheim, the Écomusée d'Alsace reassembles vernacular Alsatian buildings on an open-air site, and works better with children than either museum.
Saverne, roughly half an hour north-west on the faster services and a little more on the stopping ones, gives you the pink sandstone Château des Rohan, the ruined Château du Haut-Barr on the ridge above, and the Canal de la Marne au Rhin. Follow the canal west and you reach the inclined plane at Saint-Louis-Arzviller near Lutzelbourg, a boat lift that raises barges bodily up the hillside. Treat its status as an open question rather than a seasonal detail: the lift has been out of action for extended technical works in the past, so check with the operator that it is running before you build a day around it.
Further out, Metz takes roughly an hour and a half on most departures. These are classic-line services by way of Sarrebourg, whatever the map of the high-speed network to Paris suggests, though a handful of through trains do the leg more quickly. Metz pairs the Centre Pompidou-Metz with the Chagall glass in the Cathédrale Saint-Étienne. Nancy, roughly an hour and a half, has UNESCO-listed Place Stanislas and, to our mind more interesting, the Musée de l'École de Nancy and the art nouveau villas scattered around the city. Basel, about an hour and a quarter to an hour and a half to Basel SBB, is our pick of the lot for anyone who likes art: the Kunstmuseum in town, the Fondation Beyeler out at Riehen on a tram, and the Vitra Design Museum at Weil am Rhein, which involves crossing back into Germany on a Basel tram, a thoroughly Rhineland absurdity. Budget for Swiss prices, which are a different order from Alsatian ones.