Observant shoe gazers will note the ubiquitous square slabs of public sidewalk in Toronto are dotted with small stamps bearing a name and date. The older ones have often been worn into faint sunken relief by the erosion of millions of shoes - new ones tend to stand out on patches of light cement.

From the city's point of view, the practice of impressing names into the cement is mostly about quality control, but keeping an eye to the ground for the earliest date makes for a fun game too.

According to engineering and construction services, new stamps must follow strict set of rules regarding size and placement. As the diagram above shows, the name of the contractor must arch over the date and be bound within a rounded rectangle border. The stamp must be 22.5 x 13 cms and placed at either end of the installation or every 10 pieces, whichever is less.

Rules weren't as strict in the past. A quick scan of the nearest pedestrian walkway will yield stamps from different decades and in a range of styles. The oldest I know of is at Greenwood subway station (shown) and dates from 1946. Some bear the simple descriptor "city" for sidewalk laid by Toronto's own works department. Most sidewalk work is contracted out, however.

Keep an eye out next time you're on the street.

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Chris Bateman is a staff writer at blogTO. Follow him on Twitter at @chrisbateman.

Image: Chris Bateman