I think your models are looking okay so far, but your city looks uninhabited, and is lacking in atmosphere. Your textures are also too clean - give them more character by adding in some weathering and dirt to make them look like they’re part of the real world. Greece has a pretty harsh climate - I visited Athens some years back and in the few days we were there we experienced everything from thunderstorms to baking heat. Show some of the effects of those extreme elements in your surfaces. I worked on the city of Argos for Clash of the Titans, and we spent a lot of time weathering the city to look real. You don’t have to make everything grimy and filthy, but you definitely need some wear and tear. I hate using my work as an example, but there are a few shots of that city in my reel:
To make your city feel alive, add set dressing - stuff like market stalls, barrels, scaffolds, pathways, and, well, people! A good reference for this would be the Assassin’s Creed games. They did a great job of making the cities feel alive.
Lastly, atmosphere is really important. Lighting is a big part of this but also colour grading and atmospheric effects like distance fog, smoke, volumetric lights, etc.