The Acropolis Museum, Athens
Just down the hill from the Acropolis sits architect Bernard Tschumi's modern three-decades-in-the-making addition to the ancient site. The exterior of the glass-walled space, which holds 40,000 artifacts, reflects the Parthenon. Highlight: A replica of the Parthenon's frieze, awaiting the return of the hotly contested Elgin Marbles. newacropolismuseum.gr, admission $1.50 through 2009.
Musée Magritte Museum, Brussels
René Magritte's hometown has unveiled a sparkling new space befitting its surrealist star and filled it with his paintings, letters, and drawings. Even the renovation of the neoclassical building paid homage to the artist: A canvas that hung over the scaffolding showed a trompe l'oeil curtain pulled back to reveal a Magritte work. Highlight: Lesser-known Impressionist works. musee-magritte-museum.be, $11.25.
Punta della Dogana, Venice
Billionaire art collector François Pinault (he owns Christie's) led his organization to take over this 17th-century customs house, beating out the Guggenheim Foundation. Architect Tadao Ando transformed the space into a giant gallery to show off works from Pinault's 2,500-piece collection. Ando gutted the interior to reveal brick walls, on which you'll find an A-list of contemporary artists. Highlight: Playful Japanime from Takashi Murakami. palazzograssi.it, $21.
The Western world's largest branch of St. Petersburg's State Hermitage Museum has reopened, with 10 times more space, in a 17th-century nursing home. Highlight: The inaugural exhibit showcases over 1,800 artifacts—lavish thrones, extravagant gowns, and Fabergé jewelry—plus paintings depicting the lives of 19th-century czars. hermitage.nl, $21.
Museum Brandhorst, Munich Exactly 36,000 technicolor ceramic rods shroud the latest addition to the burgeoning Kunstareal museum district. Inside the 34,500 square feet of galleries: 150 works, including more than 25 paintings by Andy Warhol and works by superstars Damien Hirst, Bruce Nauman, and the German Gerhard Richter. Highlight: A room above the foyer designed for Cy Twombly's Lepanto Cycle, a series of 12 abstract paintings. museum-brandhorst.de, $9.75 Tuesday–Saturday, $1.50 on Sundays.