4 up, 2 down

It's not that common for appartments/flats in Edinburgh to have a basement level, but this street in Stockbridge has 2. Woweee, I don't think I have seen it elsewhere?

I have no idea why as the road does not look built up, like say the Royal Mile, and they will have dug a long way down, 100 or so years ago, just for an extra level.