An acropolis is an area of high ground. In ancient Greece, many cities were built around an acropolis. If attacked, the people could take shelter in the buildings built high above the city on the acropolis.
The Acropolis in Ancient Athens
Many ancient Greek city-states built their city around a high hill or a mound of some sort. This high hill or mound was the acropolis. If a section of high ground did not exist, the ancient Greeks built a high mound somewhere in their city to act as the acropolis. If they could, they put an acropolis on the edge of a cliff for even more protection. They built a sturdy temple on each acropolis. Some had more than one temple plus other buildings. Some city-states had more than one acropolis.
The Greeks did not build high to get closer to their gods because the Greeks did not believe their gods hung out in the heavens. They were quite sure their major gods resided on Mount Olympus. Besides that, they believed there were Greek gods and deities and spirits everywhere, including some under the sea and others flying overhead. The acropolis was designed for defense. The temples on the acropolis were built for additional protection, and as a secondary purpose were also places of worship or festivals.
At one time, there were over 2,000 different Greek city-states in ancient Greece, and nearly all of them had an acropolis. (We say nearly all because the ruins of far too many ancient city-states no longer exist, so it's impossible to know for sure, but most probably they all had an acropolis because it was the Greek thing to do.)
The most famous acropolis in ancient Greece is probably the one in ancient Athens. The acropolis in Athens is so famous that it is usually capitalized, like a proper name, and referred to simply as "The Acropolis".
The Parthenon is a famous temple. It was built on The Acropolis (in ancient Athens). It was built by Pericles around 2,400 years ago! The picture above is not a drawing of the real Parthenon. It is a building in Tennessee in the United States. Ancient Greek architecture has inspired many artists and many buildings throughout time. Greek architecture is one of the many gifts the world received from the ancient Greeks.