You'll find the Acropolis to be busiest during the afternoons, between 11 AM to 1 PM.
Is there a line for Acropolis?
There are two entrances to the Acropolis: the main one which is in the west and the side entrance (known as Dionysus Theater entrance), which is located in the southeast. If you use the main one, you should know that it is usually very crowded. You should be prepared to wait long in the line to enter the site.