The crowds are shouting again

It is already the second time since I've worked here, that there is crowd noise coming up from the streets... people shouting, voices, just a crowd making a noise.
The first time, I was wondering what was going on... a demonstration in the streets maybe...or an accident? I couldn't really think of anything else.
When I asked one of my colleagues, she said: "Well that's kind of normal here. You hear that quite often. There must be a celebrity down there somewhere."

To be honest, that was one of the least things I would have thought of.