Seagulls in Berlin

I had an inquisitive visitor on our rooftop terrace in Berlin last summer: a rather nosy and very large bird that seemed to fly reconnaissance missions on me  when I was peacefully sitting on my terrace. It came quite close, quite fast and on a direct flight path, looking me in the eye in what I found to be a rather menacing frightening look ... It was a very large seagull, a herring gull or "Silbermöwe" (Larus argentatus) checking me out. 

They were a couple. They had three kids growing up on the roof on the other side of the road in the same height as the terrace of our flat - which was quite close, 30 m across, obviously a little too close for comfort for them. They would not know I could not fly over ...

young seagulls whining for food

These seagulls have been observed to breed in the inner city of Berlin since 2010. Our terrace was only finished in 2016 on the rooftop of a new apartment block, which must have taken them by surprise suddenly finding humans at this height and in such proximity. 
They are 175 km from the  coast but either don't mind the freshwater lakes or prefer the "junk" food they find in the city. Food is not scarce here. 
On the flat rooftops they find the gravel that they like to build their nests on. 

We only observed them in their late adolescent stages just before they learnt to fly. They were constantly and loudly demanding more food; the poor exhausted parents were busy carrying goodies to their healthy strong offspring. 

practising the first short flights watched by the siblings

On July 20, they all took off early in the morning to explore the surroundings and I did not see them for several days. After that, I only occasionally saw them again, circling in the sky.

I have seen a couple returning to the same spot this year. I wonder whether they will breed here again and hope they won't mind me watching.