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Well, they are all mobile snapshots only, I am not a photographer by any means :)

I guess I just happened to capture the right composition accidentally. Plus, there are no people, the weather makes the surroundings look dingy... That may be the root of that sensation of yours.

The one where we can see the lawn, tables and chairs. Studied it a little more. I think it's because you captured a few different levels. Off to the right there's something much higher, but still lower than the camera. Then the rest is way down there.

Often height appears the same as distance would appear in a photo. That one I can see the stages or steps, all the way to the ground. Gave me that feeling like I was too close to the edge. Luckily reality kicked in, and I did not fall.

That's a good observation - people need perspective to realize distance/height.