As soon as glass is chosen as a flooring material, the first question is, "What kind of glass?" Clear glass gives views that might not be desired, so translucent glass is often favored. This bridge illustrates what can follow from using translucent glass: lighting that illuminates the floor and creates even more drama.
This house in San Francisco by John Maniscalco uses glass walkways adjacent to the stairs. With the skylight located above the walkways, the light brought to the lower levels is maximized.
This photo was taken one level below the previous photo, making it apparent that the glass walkways are stacked. Note that the lower level's glass floor is wider, and its effects are visible in the next photo.
On the lowest floor, the glass floor helps bring plenty of light to the space. It presents a soft glow that echoes the plane of the white drywall ceiling around it.
Maniscalco used a glass bridge in another project, this one also located below a skylight. Note the green color of the glass, indicating the iron content naturally in the material. This is often undesirable in such an application, but low-iron glass, as the white-gray glass is called, comes with a cost premium.
Here is one more Maniscalco project that also places a glass floor under a skylight. It just makes sense to tie the two together vertically, so they work in concert.
Glass floors need not be limited to walkways or bridges. This square patch of glass floor helps bring light to the library below.
This view shows how the cross-shaped structural members supporting the glass give the ceiling a strong character ... and an added sense of security.
Here is a library that doubles as a stairway. The tall bookshelves run across multiple floors off the stair landing. The glass floor gives this wall of books some cohesion.
And a last view positions the viewer on the glass floor, illustrating how it relates to the window next to it. The glass floor also provides visibility of the green roof, a nice touch.
In this multistory high-rise loft, a glass floor is used to bring additional light to the space below it. Sitting on a chair on a glass floor must take some getting used to!
This view from below shows some of the light coming from above, but also how objects touching the glass are in focus but those farther away are blurry.
This is probably the craziest application of a glass floor I found on Houzz, reminiscent of Philippe Starck's bar at the Hudson Hotel in New York. In both cases, a glass floor is combined with a whimsical design and some neoclassical elements. This house is interesting because of the space it overlooks.