Complex sentence: In 1837 Delaroche received the commission for the great picture the "Hémicycle," 27 metres (88.5 ft) long, a mural in the hemicycle of the award theatre of the École des Beaux Arts.
Split into simpler sentences: In 1837 Delaroche received the commission for the great picture that came to be known as the "Hémicycle,". This was a 27 metres (88.5 ft) long, mural in the hemicycle of the award theatre of the École des Beaux Arts.