Glass blocks - sward
These "kit" stacks, constructed in 1902, were "state of the art" then, but do not meet 21st century building codes.  Note the open spaces below the shelving, connecting several floors in a chimney-like stack, a fire hazard. The aisles lacked adequate space for wheel chairs.  But the translucent floors were lovely. People walked on these glass floors for 110 years! 

Note the different shapes and sizes of glass blocks.

These "kit" stacks, constructed in 1902, were "state of the art" then, but do not meet 21st century building codes. Note the open spaces below the shelving, connecting several floors in a chimney-like stack, a fire hazard. The aisles lacked adequate space for wheel chairs. But the translucent floors were lovely. People walked on these glass floors for 110 years!

Note the different shapes and sizes of glass blocks.