Hemicycle, a semicircular or horseshoe shaped debating chamber
Armitage was one of four students selected to assist Delaroche with the fresco Hemicycle in the amphitheatre of the Palais des Beaux-Arts, when he reputedly modelled for the head of Masaccio.
This commission was followed by works at the Sorbonne, namely the enormous hemicycle, The Sacred Grove or L'Ancienne Sorbonne amongst the muses in the Grand Amphitheater of the Sorbonne.
He discovered 8 Corinthian columns, remains of the water distribution pond which collected the water brought by the Roman aqueduct of Arcier, and the remains of a hemicycle that has an inner diameter of 54 meters.