THE MUSEO LAZARO GALDIANO IS AMONG Madrid’s most overlooked art museums, seldom visited by the crowds that converge on the city’s more famous galleries, such as the Prado and the Reina Sofia. But what this small museum lacks for in size it makes up for in the sheer quantity and quality of its collection. Built in 1903 to house the enormous collection of the eccentric banker and art collector Lazaro Galdiano, this ornate mansion-turned-museum has been open to the public since 1962. Among its exhibits you will find some stunning artistic and historic treasures, such as sprawling medieval manuscripts, baroque Renaissance paintings, an armory featuring suits of armor and some rather deadly looking weapons, and numerous ancient Greco-Roman sculptures and ceramics. The highlight of a visit to this museum, however, is to see the wonderful Gothic masterpieces that Galdiano collected throughout his life. Here you can find many of El Greco’s melancholic paintings, the bizarre and esoteric works of Hieronymus Bosch, and perhaps most interesting of all, the disturbing art of Francisco Goya. The museum’s collection of artwork by Goya is particularly noteworthy as it contains some of his “Witches Sabbath” oil paintings and the entire “Disparates” print series, which features haunting black-and-white sketches portraying visions as if from a datura-fueled waking nightmare. Free from 3-4:30 Tuesday through Sunday, 2-3 on Sundays.