Greece, as I hope most of you know, is a European country on the shore of the Mediterranean Sea. Greece was once a very powerful country, being the leader of the world in arts, literature and philosophy. This writeup will focus on the so-called 'Classical' period from approximately 479-323 BC. This is the time period that most people unconsciously associate with Ancient Greece.
The Classical period began at the end of the Persian Wars. Many great and memorable things were accomplished during this period, including the founding of the democratic system of government under the Athenian statesman Pericles, as well as the creation of the tragedies of Sophocles, Aeschylus and Euripides.
The greatest achievement (IMHO) of the Classical period was the founding of the philosophical schools of Plato and Socrates, which have given us, among other things, platonic relationships.
Architectural styles varied greatly during this period. Common at the beginning of the fifth century BC was the Doric style of architecture, displayed in buildings such as the Parthenon. This was displaced by the Ionic style, the oldest example of which is the Erechtheum, a temple built on the Acropolis of Athens between 421 and 405 BC. In the middle of the fourth century BC the Corinthian style of architecture reached full development. This was the most ornate of Ancient Greek styles, commonly seen on Greek/Roman temples.
The classical period was the height of Ancient Greece's cultural and political development. For further reading on this topic I recommend Plato's The Last Days of Socrates and Ancient Greece : A Political, Social, and Cultural History by Sarah Pomeroy, Stanley Burstein, Walter Dolan and Jennifer Tolbert Roberts.
NOTE: As stated in the beginning of this write-up, this is not a thorough study of Ancient Greece. It concentrates solely on the Classical period, and skims over that. If you are writing a school assignment using this write-up as a sole reference, you will fail.