They appear to merge with the landscape and the sky, perhaps nothing more than a figment of the imagination: the five softly shimmering prisms at the new branch of the Louvre in Lens, a city in northern France. Kazuyo Sejima and Ryue Nishizawa of SANAA have created museum structures of incredible delicacy, yet free of sculptural indulgences. At first glance it is very simple architecture, all visible details are restrained. But arriving at such loftiness requires intricate tectonics, and, above all, a complex planning process. The transparent glass hall is stabilized by the two corners of the adjacent pavilions; there is no horizontal bracing within the entrance hall itself.

Li Xiaodong’s library in the Chinese town ­Liyuan also strikes us as refined and ­multi-faceted. Its skin of twigs and the accompanying play of light and shadow transform the interior into a sensual setting well suited to reading. The different levels, projections and landings create a spatial variety that seems complex.

These two ­examples are representative of how closely ­entwined the terms ‘simple’ and ‘complex’ are in all of the projects in this issue. Because a ­simple entity may make a very complex impression – and vice versa.