Louisville sits at the one place where the Ohio River used to fall apart. Just upstream of downtown the river drops over a limestone ledge, the Falls of the Ohio, which once forced every boatman to stop, unload or pay a pilot, and that portage is the whole reason a city grew here. On the Indiana bank, the fossil beds exposed at low water are some of the oldest and richest in North America, a seabed of Devonian corals that you can walk across in late summer. George Rogers Clark started his western campaign from the settlement across the water in what is now Clarksville.
For a rider coming down from Indiana, the approach is the Interstate bridges and a rapid change from hills and farm roads to a proper city, with a skyline, river barges and a huge amount of freight traffic. Take it calmly, pick a Sunday morning if you can, and use the pedestrian bridge at the old Big Four rail crossing as your viewpoint, because the water is the best thing here. Jeffersonville, Clarksville and New Albany are the Indiana-side towns that share the river, and they all have good lunch options without the downtown crowds.
Culturally the city carries plenty. Churchill Downs hosts the Kentucky Derby on the first Saturday of May, and the Twin Spires are an odd, charming sight even on an ordinary day. Bourbon is made across the state and the city leans into it, with distilleries and tasting rooms scattered around the old warehouse district. The Louisville Slugger bat factory is hard to miss thanks to the giant bat leaning against its wall, and Muhammad Ali was born here and is honoured with a museum on the waterfront.
Practically, this is a big city. Fuel, food and a bed are everywhere, parking for a bike is rarely a problem, and the main thing to plan for is the humidity. July and August feel like riding through warm soup. Come in spring or autumn, give yourself an hour at the river, and you will understand why the stop sits on the route.