These https://farm5.staticflickr.com/4511/37602888282_c8802fdff8_o.jpg
are all over and it seems like parts of the buildings were buried under the ground.

I know that there used to be floods but it doesn't explain why this would be done in cities that were not affected by flooding at all.

EDIT: I saw some people mention that these are simply basements. However, it is obvious especially from the additional pictures I attached, that these were not built as basements originally - they look like the exact copy of the upper windows but partially buried.