Built on the ruins of Lutecia's Roman Baths, the Hôtel de Cluny has been a museum since medievalist Alexandre Du Sommerard established his collection here in 1844. The over-the-top mansion was a choice location for such a collection; the 15th-century building was created for the abbot of Cluny, leader of the most powerful monastery in France. Symbols of the abbot's power literally surround the building, from the crenellated walls that proclaimed his independence from the king to the carved Burgundian grapes, symbolizing his valuable vineyards, twining up the entrance. The scallop shells Coquilles-Saint-Jacques covering the facade are a symbol of religious pilgrimage, another important source of income for the abbot; the well-traveled pilgrimage route to Spain, rue St-Jacques, once ran just around the corner. The highlight of the collection is the world-famous Dame à la Licorne (Lady and the Unicorn) tapestry series, woven in the 15th or 16th century, probably in Belgium. The tapestries are an allegorical represention of the five senses. In each, a unicorn and a lion surround an elegant lady against an elaborate millefleur (literally, 1,000 flowers) background. The enigmatic sixth tapestry, Mon seul désir, is thought to symbolize love or understanding. The collection also includes the original sculpted heads of the Kings of Israel and Judah from Notre-Dame, discovered in 1977; the statues were decapitated off the cathedral during the Revolution and the heads hidden by a nobleman near today's Galeries Lafayette. You can also visit the remnants of the city's Roman baths -- hot (caldarium) and cold (frigidarium), the latter containing the Boatmen's Pillar, Paris's oldest sculpture. A charming garden is laid out in the medieval style, using the flora depicted in the unicorn tapestries.