Complex sentence: Modern glass bricks were preceded by Falconnier Hollow Glass Bricks in the late nineteenth century, which were blown glass bricks available in multiple colors shaped in molds while the glass was molten.
Split into simpler sentences: Modern glass bricks were preceded by Falconnier Hollow Glass Bricks in the late nineteenth century. Falconnier Bricks were blown glass bricks available in multiple colors and were formed in molds while the glass was molten.