Complex sentence: The parent athletic club, Panellinios Gymnastikos Syllogos, was founded in Athens in 1891, making it one of the oldest sports clubs in Europe and had a team of gymnasts compete at the 1896 Summer Olympics in Athens.
Split into simpler sentences: The parent athletic club, Panellinios Gymnastikos Syllogos, was founded in Athens in 1891, making it one of the oldest sports clubs in Europe. It had a team of gymnasts compete at the 1896 Summer Olympics in Athens.