Though it may seem paradoxical, the Channel Tunnel linking England and mainland Europe, which turns 30 this year, has fueled an increase in maritime traffic in the Strait of Dover, making Calais France’s No. 1 ferry port. To handle demand, as well as today’s larger ships, a new harbor opened in Calais in 2021. Rising 125 feet between the old and new ports, this traffic-control tower, by Lille-based architects Atelier 9.81, came into service in early 2023. Fragmenting their concrete structure, which is two-thirds prefabricated, into a Jenga-like pile of cantilevered boxes, the architects textured its surface with evocations of dials, nautical charts, and sedimentary rocks.