Christ & Gantenbein’s new bridge in Aarau, Switzerland, doesn’t just connect two different sides of the Aare river — it also narrows the gaps between several periods of local architectural history. Working in collaboration with engineering studios WMM Ingenieure and Henauer Gugler, the Basel-based architecture practice developed a row of five variable-width arches that are a marvel of contemporary construction. Yet the structure’s light grey board-formed concrete also successfully harmonizes with Aarau’s older stone buildings, which include no shortage of medieval castles.

In another deft balance of past and present, a portion of the new infrastructure partially rests on two caissons that were preserved from the river’s previous overpass, which was built in 1949. (Earlier iterations date all the way back to the Roman Empire.) Spanning 119 metres long and 17.5 metres wide, the present-day Aare bridge accommodates automobile traffic, pedestrians and cyclists with equal grace. In addition to revamping the riverbank on either end, the project also encompasses fresh landscaping updates (by August + Margrith Künzel) to a pair of riverside urban promenades. Thirteen years in the making, the result is a civic landmark for the ages.