Why do we use "in" in the phrase "in front of"?

I just realized I can't quite make out why we use the word "in." The meaning of front is generally a surface, a side - not a space you can be "in," so how did that happen? Is it an artifact of an older meaning of "front"? Was "front" also once the name of the space in front of something?

After all, "in the front" does refer to a space (I exclude "at" because "at" by nature converts an object to a location), yet particularly refers to an interior (real or abstract) space. But all you do is drop "the" and now it's an external reference. Curious.

It's so hard to Google this or search it on here because so many questions use the phrase in asking about word choices, order, etc.

Solution 1:

If an object is “in front of” something, it is in the space that is in front of the object. I have provided a simple diagram below to model this idea:

Edit

Perhaps this quote from Wiktionary will help:

At or near the front part of (something). In the presence of, in view of (someone). Not in front of the children! Located before, ahead of, previous to (someone or something). I'll take the one in front of the black one.