I was traveling through Vermont this weekend and walked around the
pedestrian mall in downtown Burlington. One of the buildings on the mall
was the Ethan Allen Engine Company #4, as shown here. Note the concrete
sidewalk across the front of the building, which extends around all four
sides of the building. It's actually 2 -3 squares wide on the sides and
back of the building.

http://i440.photobucket.com/albums/q...ps04230033.jpg

Each sidewalk square is almost 5 feet on each side. As you can see from
the images below, each square is inside of a metal frame and each square
has some sort fitting in the center of it. The fitting has an outer
circle and domed center with a hole in the middle. The top of the dome
is level with the concrete surface. Only the sidewalk squares that
surround the old firehouse have the frames and fittings. They butt up
against the sidewalk squares that surround the City Hall next door and a
sidewalk through City Hall Park behind it. Those sidewalk squares are a
different size and have no frame or fitting. They appear to have been
poured at a different time.

The fittings were filled with dirt and slush and it was too darn cold
for me to start digging around to clean one out for a better look.

Here's the fitting, with my sneaker nearby for size comparison:

http://i440.photobucket.com/albums/q...9317653551.jpg

Here's a couple of images of the metal frame around each section:

http://i440.photobucket.com/albums/q...9317718938.jpg

http://i440.photobucket.com/albums/q...9317823080.jpg

Anybody know the purpose of these frames and fittings? Could the fitting
be for some sort of "mud jacking" to keep the square level? Could they
just be a design feature?

Does that fact that these fittings are only found around the fire house
have anything to do with it or was that just some old time contractor's
way of building sidewalks?