Complex sentence: The oldest parts of the palace are Langton's Chapel and its crypt, both of which date back to the 13th Century, although they suffered greatly from damage in the Second World War, they have seen been extensively repaired and restored.
Split into simpler sentences: The oldest parts of the palace are Langton's Chapel and its crypt, both of which date back to the 13th Century. Although they suffered greatly from damage in the Second World War, they have seen been extensively repaired and restored.