Complex sentence: The walls of this great hall were decorated with group portraits of the different companies of the civic guard, including Rembrandt's "The Nightwatch" and works by Nicolaes Eliasz.
Split into simpler sentences: The walls of this great hall were decorated with group portraits of the different companies of the civic guard. These group portraits included Rembrandt's "The Nightwatch" and works by Nicolaes Eliasz.