Complex sentence: The building's original entrance sequence was much compromised by these changes and the later additions of raised concrete walkways around the building to serve the neighbouring Queen Elizabeth Hall, Purcell Room and The Hayward, built in 1967/8 and also part of Southbank Centre.
Split into simpler sentences: The building's original entrance sequence was much compromised by these changes and later additions of raised concrete walkways around the building. The neighbouring Queen Elizabeth Hall, Purcell Room and The Hayward were added in 1967/8 and are also part of Southbank Centre.