If you can't make it to Madrid's Prado, then consider Seville's Museum of Fine Arts your second-best option. Hailed as having one of the most impressive art collections outside of the capital, the museum is well worth the stop, and for more than just the artwork.
The Museo de Bellas Artes (as it is called in Spanish) dates back to the 1830s, and is situated in what used to be a 16th-century convent. Within its walls, explore works – largely religious in subject matter – dating from the Gothic period to the 20th century, and by greats like Murillo, Zurburán and even El Greco. Beyond just paintings, you'll also find other items on display, ranging from sculptures to ceramics and furniture.
But don't just come for the art: The building alone is worth scoping out. During your visit, you’ll pass through an entry hall adorned in Seville’s hallmark colorful tiles, then wander through tranquil patios and a garden-filled cloister, and finally discover museum nirvana below the elaborate ceiling of an art-filled former chapel. Even better: Given the museum's off-the-tourist-track location just north of the main sightseeing area, expect your visit to be relatively crowd-free.