"Can not" vs. "cannot"

"These buildings can not be constructed in cities."

I found this sentence in the Wiki. It contains a mistake that individuals with English as a Second Language often make, and also, sadly, many other English-speaking individuals whose education was lacking.

The intent of the sentence is to specify that a player is unable/incapable of constructing "these buildings" in cities; that is, the construction of said buildings is impossible/prohibited.

The correct sentence would read: "These buildings cannot be constructed in cities." or "These buildings can't be constructed in cities."

Saying that something "can not" be done specifies that there is the option not to do it.

For example, John says to Alan: "I don't want to go on another date with Mary because she doesn't share my interests." To which Alan replies: "Well, you can not go on another date with her." (With a slight pause after "can" and a slight emphasis on "not".) But it is more common to say "Well, you don't have to go on another date with her." (With a slight emphasis on "have".)

So, while a player always has the option of not constructing certain buildings in cities ("can not"), he doesn't always have the option to do so; that is, sometimes, for certain buildings, no option to construct them in cities exists (it is impossible), and he cannot.