The Levee is replaced by the following unique building:
Build the Levee to receive a bonus production from river tiles.
When placing a city, it may be unclear whether a tile is adjacent to a river. For example, tiles which touch the source of a river, but which are "behind" the source with respect to its direction of flow, are not riverside. Hovering over a tile and checking the tooltip for Fresh Water usually helps, but may be ambiguous if the tile is also adjacent to a freshwater lake. Another potential indication is the tile's yield: if the tile has an extra beyond that provided by any resources or improvements, then the tile will surely be riverside. However, the +1 may be obscured by a Forest or Jungle.
The earliest human civilizations all grew up along the banks of rivers. Yet when rains grew heavy, the Nile, Indus, Tigris or Yangtze became a danger to those on their shores. The Levee, also known as a dam, is a wall of earth or stone, constructed to hold back encroaching waters. The ancient Egyptians were among some of the most sophisticated levee builders, channeling the Nile in order to provide water for cities and crops. Today levees provide hydroelectric power to populations throughout the world.