Urban City Pack v1.2
https://assetstore.unity.com/packages/3d/environments/urban/urban-city-pack-34832

As a fully realized urban city environment, this pack is built to highest AAA standards for environmental art inside Unity 5. All the assets have been created efficiently to ensure both smooth frame rate and low memory. This pack contains over a dozen pre built buildings, as well as over 100 modular building assets allowing the user to mix and match pieces. To go along with the buildings, the world is fitted with dozens of standard assets, a modular road pieces, and over 30 seamless PBR materials, all ready to be dragged and dropped in game.