From Liquipedia Overwatch Wiki
Rialto is an Escort map in Overwatch that was released on May 3rd, 2018, and is available in competitive play. The map is located in Venice, Italy.
The map was initially playable in a night time mode for the Overwatch Archives 2018 Retribution PvE mode.
Top-Down View of the Map
Image courtesy of Statbanana: https://statbanana.com/images