Task: Question Answering
Input (English): Context: You may know your mother, but how well do you really know Mothers' Day? Cards, flowers, sales, TV specials, and a day off for someone who really deserves it -- those are what probably come to mind for many people when they think of Mothers' Day. But there's more to the story. The earliest Mothers' Day celebrations were held during spring in ancient Greece. The celebrations honored Rhea, the mother of the gods. During the 1600's, England celebrated a day called Mothering Sunday. On this day even servants were given the day off to spend with their families. A mothering cake was even served with the family meal. In the US, Mothers' Day began in 1872 when Julia Ward Howe, who wrote the words to the famous song The Battle Hymn of the Republic, suggested it as a day devoted to peace. But it didn't really become popular until 1907 when Anna Jarvis started a campaign to honor mothers. She believed that mothers could help people get over the pain they experienced during the Civil War. The US isn't alone in devoting a day to mothers. Many other countries including Denmark, Finland, Italy, Turkey, Australia, Japan, and Belgium also honor their mothers in May. Other countries honor their mothers at different times of the year. Learning more about Mothers' Day and celebrating Mothers' Day are important, but probably not as important as understanding what your own mother, or grandmother, or aunt has really done for you. And that will certainly be appreciated more than one day in year. 
 Question: Where was the earliest Mothers' Day celebrated?
Output (English): in ancient greece.