A new map set in the Italian city of Rialto is currently available in the Overwatch PTR.
Rialto is a payload escort map and will be set during the daytime. The new map was first introduced as a part of the Retribution event, where a team of four players take on Talon soldiers.
The Retribution event is happening now, and will run until April 30. There has been no word on when the Rialto map will make its way into the normal map pool. Blizzard has said that new maps and characters like Brigitte and Rialto will have to wait until Season 10 for Rialto to be included in the competitive map pool and roster.