What you saw is one of its reference markers, located off the Port Authority's property at ground zero but used to determine the property's exact location.

Hanks was first shot against a blue screen along with reference markers so that he could line up with the archive footage.

In descriptions of boundaries which served to clarify which property belonged to whom, it was used as a significant reference marker.

The states of Nevada and Ohio use reference markers very similar to California's postmile markers.

Ohio's system is nearly identical to California's with its reference markers listing the route number, 3-letter county abbreviation, and mileage through the county.

Many of the reference markers along NY 443 still bear the number "43".

At the beginning of NY 787, some reference markers have the letter "I" along the top (route) row.

The section south of here is marked only with reference markers, and the section north only with county mileposts.

The reference marker corresponds to the station of the alignment in the construction plans.

The original east-west orientation of NY 300 is reflected in the mileage given on the route's reference markers.