Simplify the following text for a Grade 6 native English-speaking person.
Original: The Three Choirs Festival is a music festival held each August alternately at the cathedrals of the Three Counties ( Hereford , Gloucester and Worcester ) and originally featuring their three choirs , which remain central to the week-long program .
Simplified: The Three Choirs Festival is a festival of classical music which is held every year in August . The choirs from three cathedrals take part in many of the concerts .