Bottom line: choose Madrid for art, history and traditional Spanish atmosphere; choose Barcelona for Gaudí and the beach. Madrid, Spain's capital, offers grand plazas, top-tier museums (the Prado–Reina Sofía–Thyssen 'art triangle') and a more traditional, fast-paced urban feel — its strengths are nightlife, cultural events and top tapas bars. Barcelona wins on its Mediterranean beaches, Gaudí's Sagrada Família and Park Güell, and a more relaxed coastal pace. If you only have a day or two and want to cover the main sights easily, Madrid is the easier starting point; the two cities are about 2.5–3 hours apart by high-speed AVE train.