Leon was founded in the 1st century B.C. as a Roman military camp. Its name derived from the Lation legio, from the Roman legion that was stationed there to secure the transport of the gold extracted in Las Medulas to Rome. After attacks by Visigoths and Muslims in the 8th and the 9th Century, Ordono II made it capital of his Kingdon of Leon in 914, and Leon became one of the most prominent Christian cities in Iberia. Pilgrims on their way to Santiago de Compostela would pass through Leon. Trade, crafts and cattle breeding were responsible for the city's prosperity and growth until the 16th Century when a period of economic decline set in.

The city's most famous architectural landmark is the Santa Maria Cathedral, also known as 'the House of Light'. It was built in the place of 2nd-century Roman baths that King Ordono II, Leon's most famous ruler, converted into a palace. A master of the name of Enrique designed the cathedral in the mid-13th century, and its construction went on until the late 16th Century. The building is a masterpiece of the Gothic style. Its façade, an elaborate lacework of stone, is crowned by a clock rower and flanked by two ornate belfries of different height and design. A large rose window dominates the central section above the three pointed-arch, sculpture-decorated portals. The interior is just as rich. Its most remarkable feature are the invaluable 1800 square metres of stained glass windows, one of the world's masterpieces of this medieval art. The choir was built by prominent artists: Jusquin, Juan de Malinas and Copin of Holland. The Renaissance retrochoir is adorned by alabaster statues. A silver urn containing the relics of the town's patron, St. Froilan, is kept in Mai Chapel which also contains an elaborate altarpiece. A rich collection of sacred art can be seen in the Cathedral's Museum, including 50 sculptures of the Virgin.

Another monumental building is the Royal Pantheon in the Basilica de San Isidoro where members of the royal family of the Kingdom of Leon were buried. It houses a fine collection of Romanesque paintings. The boarding house of San Marcos has a beautiful Plateresque façade. Palacio de los Guzmanes, site of the provincial parliament, is remarkable for its attractive Plateresque patio. Casa de Botines is an early work of the famous architect Antoni Gaudi. The newly opened Museum of Contemporary Art designed by Mansilla and Tunón has been praised as a masterpiece of modern architecture.