This is the 51st in a series of walking tours highlighting the sites and stories of diverse districts of the Paris region I’d long been intrigued by the Cours de la Reine, the walkway carved out along the Seine for Marie de Medici, who became Queen Consort of France when she married Henri IV in 1600. She was nostalgic for her native Florence and missed the garden strolls she’d enjoyed there, so she had this kilometer-long park created along the Seine, just west of the Jardins des Tuileries.    The Italian word corso, or “pathway” in English, became cours in French, used to describe the area, shaded by rows of tall trees, where Marie and those nobles to whom she gave permission could promenade or take a carriage ride, enjoy the river views and feel safe knowing that the general public would not be allowed in. A ditch dug around the edge, fencing and gated entrances saw to that.   Théodore Gudin (1802-1880). “Le Cours-la-Reine”. Huile sur toile, vers 1828. Paris, musée Carnavalet. On a map of today’s Paris, the Cours de la Reine stretches from the Place de la Concorde to the Place du Canada. Its continuation, leading further west to the Place de l’Alma, has been renamed after France’s World War I ally, Albert I, King of Belgium. Completely open on both sides and home to a number of imposing statues, the walkway is perfectly suited to a quiet meander with riverside views. Even better, there’s a Ville de Paris art gallery close to both ends, the Musée d’Art Moderne and the Petit Palais, each offering free entry to its permanent collection.    I began at the Musée d’Art Moderne, housed in the Palais de Tokyo, built in 1937 for the International Exhibition of Arts and Technology. Gazing uphill at the colonnades separating the east and west wings, each a series of stark rectangular blocks relieved here and there by classical-inspired bas-relief, I wondered if it was open. There seemed to be no one around. But, after climbing the wide central steps, I found a way in and went to do a little exploring. I’ll just wander, I thought and see what strikes me from the collection of 20th century art, which spans such movements as Cubism, Fauvism, Abstraction, and New Realism.