Complex sentence: The Carlton Citadel Hotel is a 150-year-old building which had government troops based there, and in a statement from the Islamic Front was called a barracks; troops had been based there for 2 years.
Split into simpler sentences: The Carlton Citadel Hotel occupied a 150-year-old building in which government troops had been stationed. A statement from the Islamic Front referred to the building as a "barracks"; troops had been based there for 2 years.