Ski Grandvalira: The largest ski area in the Pyrenees, with over 200 km of pistes spread across seven sectors. Soldeu and El Tarter are the main bases. The skiing is genuinely good, the lift infrastructure is modern, and prices for equipment, lessons, and apres-ski are lower than in the Alps.
Walk the Romanesque trail: Andorra has an extraordinary density of pre-1200 churches for a country this size. The best are Sant Joan de Caselles in Canillo, Santa Coloma near the capital, and Sant Miquel d'Engolasters above Lake Engolasters. None requires more than a short detour from the main road.
Casa de la Vall: Free guided tours of the old parliament building in Andorra la Vella give a quick, human-scale account of how this unlikely micro-state has governed itself for seven centuries. Worth 30 minutes of anyone's time.
Caldea thermal spa: The vast glass tower in Escaldes-Engordany looks absurd and works brilliantly. Fed by natural springs at 68°C, the complex has indoor and outdoor pools, lagoons, and treatment rooms. Best on a cold afternoon after a day on the mountain.
Shop the duty-free mile: Avinguda Meritxell and Avinguda Carlemany form a 1.5 km strip of shops where electronics, perfume, tobacco, alcohol, and luxury goods sell at Andorran IGI rates of 4.5%. It's unabashedly commercial and surprisingly good fun if you're in the market for anything on that list.
Hike the Coma Pedrosa: At 2,942 metres, this is Andorra's highest peak. The standard route from Arinsal takes about four to five hours return and is manageable for fit walkers. The views on a clear day extend across the whole country and well into Spain and France.