In 1900 the Chicago River was made to run backwards. The Sanitary and Ship Canal drew its current inland, away from Lake Michigan, reversing a channel that had spent decades carrying the city's waste into its own drinking water. The engineering held. More than a century later that borrowed current still moves sightseeing hulls through the middle of the Loop, and the premise of any Chicago cruise brunch tour is straightforward: the river is the oldest gallery in the city, and the buildings along it were designed to be read from the water. Before it was a promenade, the river was a factory floor. Lumber schooners unloaded at South Water Street. Grain elevators, tanneries and coal yards crowded both banks, and in 1871 the fire crossed the water and took the North Side with it. Congestion on the rebuilt channel forced an engineering answer. Local designers refined the trunnion bascule — a counterweighted leaf pivoting on a fixed axle — first at Cortland Street in 1902, and repeated it so widely that Chicago now holds more movable bridges than any other city. The painted steel of those bascule bridges, raised in sequence for sailboat traffic, still sets the rhythm of the downtown waterway. The architecture reads chronologically from the deck. The Wrigley Building of 1921 wears glazed terra cotta, scrubbed white for its own floodlights. Tribune Tower answers in 1925 Gothic limestone, its base studded with fragments taken from the Parthenon, the Great Wall and Notre-Dame. Bertrand Goldberg's Marina City went up in 1964 as twin concrete towers with boat slips beneath the apartments, a city-within-a-city built for workers who refused the suburbs. 333 Wacker Drive curved a green glass screen along the river bend in 1983, mirroring water that is rarely the same colour twice. The Merchandise Mart, finished in 1930, was briefly the largest building on earth by floor area and carried its own postal code. A Chicago River architecture cruise passes all of it within a few bends. What makes the stretch matter now is access. The Riverwalk's final blocks opened in 2016, converting a service corridor into a continuous public edge at water level, and the architectural narration offered aboard Chicago cruise brunch tours has become one of the more reliable introductions to the skyline. Guides name structural systems rather than celebrity tenants: the braced tube of Willis Tower, completed in 1973 at 110 storeys, the exposed concrete frames of the 1960s, the setbacks forced by zoning. Docks sit at 455 N Cityfront Plaza Drive, below Tribune Tower, where the river meets the lake. From that point the view is almost entirely vertical — Chicago landmarks stacked, dated and legible, which is what the city has always asked of the people who come to look at it.