Complex sentence: It has been around for quite a few years and has been changed quite a bit in that time, the coutyard used to open to the outside, but a new section was built on, closing in the courtyard.
Split into simpler sentences: It has been around for quite a few years and has been changed quite a bit in that time. The courtyard used to open to the outside, but a new section was built on, closing in the courtyard.