Well if by visiting a person you mean an employee, I believe business hours are 8-11pm. However you should call ahead of time, to see if they are working. They could very well be on a day off or temporarily out of the office in the field. If you mean someone that has been taken into custody, I think you need to call before hand because that person may have already been released from jail or transported to a different facility in preparation to go to court.
Visit who? Someone that works there? Ask them! This is the Police Administration Building, not a jail.
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