Was there a time during the Roman Empire which can be considered a "high point"? If so, what made it the "high point"?

I would say that the high point or golden age of the Roman
Empire was very early in the actual Imperial period -- during the reign of the Emperor
Augustus Caesar.  During this time, Rome was becoming more and more powerful in military
terms and it was undergoing something of a golden age in terms of culture.  Augustus was
the one, after all, who said that he found Rome as a city of brick and left it as a city
of marble.

Augustus's reign was a time when Rome was strong
and when it was enjoying a fairly good period in terms of the kind of government it had
and in terms of its material culture.  These things combine to make his reign a high
point in Roman history.