There are multiple buildings around Rome that can be renovated. These buildings can only be renovated once the Borgia tower has been destroyed in the area. Once its down, buildings can be renovated. Walk up to a un-renovated building, press and select the option of “Renovate.” The building will then be open for business and will increase your total revenue. Buy five and the achievement will unlock. Renovating any building in the Antico district will count toward the achievement.
The Antico district is the Southern-most district.