The Athenian calendar is a way that people in ancient Athens, a long time ago, used to keep track of time, like how we have months and days and years.
The Athenian calendar had a few differences from our calendar today. Instead of 12 months, the Athenian calendar had 10 months. Each month was named after a specific god or goddess that the Athenians believed in. For example, the first month was named Hekatombion after the goddess Hekate.
Another difference is that the Athenian day started at sunrise instead of midnight, like we do today. So if the sun came up at 6 am, that was the beginning of the day, and if it set at 6 pm, that was the end of the day.
The calendar also had special days that were considered important. One example is the festival of Panathenaea, which was a big celebration of the goddess Athena. This festival happened every four years and everyone in Athens would take part in the festivities.
Overall, the Athenian calendar was a way for people in ancient Athens to keep track of time and important events in their lives, just like we do now.