Complex sentence: The present Caversham Park House, built in 1850, is occupied by BBC Monitoring, which is a section of the BBC World Service that analyzes news, information and comment gathered from mass media around the world.
Split into simpler sentences: The present Caversham Park House, built in 1850, is occupied by BBC Monitoring. This is a section of the BBC World Service that analyzes news, information and comment gathered from the mass media around the world.