More Thessaloniki

It seemed to me that Thessaloniki was a city of apartment buildings. Once you got away from the waterfront, there was very little open space in the city--just tall buildings and roads. So, here is a gas station. Right there, under someone's apartment, is the Shell station.But, then, you come across something like this...

These ruins are surrounded by apartment/shop/restaurant buildings. And people just walk by like they aren't there. I wonder how long you have to live with these to stop noticing them. (Kind of like I don't notice the Civil War era cemetery I drive by a few times a week.) How many times do people walk under this arch ...

and miss this detail?