Complex sentence: Embedded in the floor of the library is a mural of "La Amistad,"--which school tradition says must never be stepped upon--referring to the mutiny by slaves, who took control of that ship and later won their freedom.
Split into simpler sentences: Embedded in the floor of the library is a mural of "La Amistad," which school tradition says must never be stepped upon. The mutiny by slaves, who took control of the ship and later won their freedom.