Complex sentence: Built in the Gothic Revival style, the present Centre Block is the second iteration of the building, after the first was destroyed by fire in 1916; all that remains of the original building is the Library of Parliament, at the rear of the Centre Block.
Split into simpler sentences: Built in the Gothic Revival style, the present Centre Block is the building's second iteration. The first was destroyed by fire in 1916; all that remains of the original building is the Library of Parliament, at the rear of the Centre Block.