Having seen off Chipperfield, Hadid and OMA in a 2009 competition, Christ & Gauntbein has unveiled a controlled exercise in materiality, functionality and space making for the new extension. As the people of Basel will proudly tell you, the works in their Kunstmuseum belong to probably the oldest municipal art collection in the world, founded in 1661 when the city bought up the treasures amassed by local burgher Basilius Amerbach. Since 1936, its holdings have been displayed in a building of subtle severity by German architect Paul Bonatz and Basel based Rudolf Christ. Now, exactly 80 years later, the museum has unveiled a 100 million Swiss franc, 8,000sq m extension that, by a quirk of history, was designed by Christ’s great nephew, Emanuel, and his partner Chritoph Gantenbein. The museum, composed of three modern buildings, houses extensive collections of contemporary, modern and 16 to 18th century European art. The modern art collections are strong in Russian artists as well as American painters and sculptors. Also extensive holdings donated by Picasso and Frank Stella and patrons of Alberto Giacometti. As Emanuel Christ is quick to point out, he never met his great uncle nor had any particular connection with him. But he and Gantenbein did feel a connection to the historic Kunstmuseum building, which they knew by heart from having long frequented its galleries and its popular café. A mixture of beaux arts grandeur and axial planning, modernist functionalism and splendid Swiss craftsmanship, the Bonatz and Christ building sits four square in a suit of stripped Italian Romanesque, the severity of its orthogonal fenestration and bands of grey stone set off by an arcade of round headed arches on historicising capitals.