The Liverpool game in January 2019 was indeed up there due to tension, nerves, excitement of what it all meant, as was the United game in 2012, but for sheer noise, I've never heard anything like the Hamburg European quarter final, and I've been going since the 70s. I remember watching the away leg in the pub the week before. Ireland scored in the first minute to put us 1-0 up and I thought we were going to stuff them. For the next 89 minutes, we got absolutely battered and were lucky to escape with only a 3-1 defeat. I remember the start of the home leg starting very noisy but then being punctured as Hamburg scored again, and silence and tumbleweed descended. As City walked back to the centre circle to kick off, a rumble started and gradually gained volume until it became absolutely deafening. I recall Caicedo putting us 2-1 up and thinking my ear drums were going to burst. The volume was at "Aguero" levels for about 80 minutes and you could see the Hamburg players wilting. Elano smashed one against the bar late on which would've taken it to extra time. Remember that these were the days before we got in the Champions League. As stated by many, there have been countless memorable nights, but for sheer sustained noise, this one wins for me.