There is an intermittent rattling noise in our office which it turns out everyone can hear, which is quite reassuring because I was wondering if the fans on my office desktop were maybe going (it and they date from late 2017). It turns out that this is coming from work being done on the roof, which we are just underneath.

It's less charming that raccoons (or squirrels) holding gymnastics competitions on the roof, although it is happening at a more reasonable hour than 'the dead of night'.