We chose the apartment because it's located near a metro stop and many people mentioned it was quiet. While the apartment is only 8-10 minutes from a metro stop it was very noisy at night.
We arrived at the apartment on a Wednesday afternoon, did some shopping and sightseeing and returned to the apartment about 9 pm. All was quiet until we went to bed at 11 pm. As soon as we got in bed we heard a loud noise/crash just below us in the art gallery located on the floor below us. A few minutes later we heard hammering/drilling/and other building or construction noise from just below us. About 11:30 pm we went to see what was going on. We saw the area where the noise was coming from but couldn't get anyone's attention to ask them to stop. Finally, about 12:30 am the noise stopped.
On Thursday night, we arrived back about 11:00 pm. As we walked to the building we passed a restaurant/bar on the corner that was playing loud booming music. When we got inside the apartment the music was shaking the walls. We went to the area downstairs again to see if the same people were making different noise that night. This time we were able to speak to the workers there and they said it's very common for restaurants/bars to play loud music well into the night on Thursdays. There was no point in trying to sleep until the noise/music finally stopped at 1:00 am.
On Friday night, we arrived back about 10:45 pm to a party going on just below us for an art show in the gallery. There were 30-50 people just below and beside us. Of course, no party is complete without music with a pounding bass. It sounded like the party was in our living room. The party/music/noise finally ended about 12:30 am.