First, to address the issue of your last, edited sentence ("[the dictionary] says that a place could see a event, but does not say a place could see a person."), and your similar comment:
In this case the event is the person. The noun phrase can be read as ...[the milestone of] its one millionth runner on Sunday since the race's inception in 1970. Although the one millionth runner is actually named, what is really being talked about in this sentence and in the article as a whole is numbers of runners. Each sentence in the article reports on a certain number of runners.
I have added another example (using a time) to the end of this answer.
Yes, the example sentences for Definition 14 include one that has the same usage:
The last decade saw many technological advances.
14 also has an example with city as the subject:
The city has seen a lot of growth in recent years. [= the city has grown a lot in recent years]
Going with the above rewrite, you get:
[= New York City also had its one millionth runner on Sunday since the race's inception in 1970.]
It is not too far from 13 'to experience something', thus
New York City also experienced its one millionth runner on Sunday since the race's inception in 1970.
Additional example, using a time (a certain year):
Eli Whitney invented the cotton gin in 1793.
One could also say
1793 saw the invention of the cotton gin by Eli Whitney
1793 saw Eli Whitney invent the cotton gin.