1) Sharing a wall with another family. I haven't lived in an apartment or anything like it since I was 12. The mysterious thumpings and bangings that come through the shared wall still make me jump and wonder what the cats did.
2) Dramatic Neighbors. A family across the street have regular knock down drag out fights that make it to the street. Today the local police attended the event.
3) Trains. We live VERY close to active train tracks. Trains run mostly at night. Since the tracks run parallel to the main road where our street is, and we are close to that road, they cross a lot of other smaller roads, and so they signal frequently -- at every crossing. Sometimes I can feel the floor or the bed shake when a particularly heavy train goes by.
4) Easing around furniture. Yeah, I miss having space. The whole "charming, cozy space" thing is lost on me.