Good questions to ask at the end of an interview

I like to ask questions which flow naturally within the interview, for example, if the partner mentions in his brief intro s/he has been at X firm for 20 years, I might ask 'why have you been at this firm for so long'.

If they have mentioned a particular region or industry they work in, I might ask them questions surrounding those points.

It really depends on what YOU want to ask.

I hope this helps.
 
I agree with @Salma. Most interviewers will give a background about them. I do try to link back to that. Which guide or interview prep note I’ve read always mentions building rapport with the interviewer. I find it hard to do this when it’s just a quick back and forth question/answer exchange. So for me, I find it’s a good opportunity to build such a rapport.

But otherwise, it really is an opportunity to ask what lever you want!!