You are correct, that people go through an entrance (to get into the building). They then can take the route from there to Point A, then to Point B and so on.
However, for whatever reason -- clarity, common practice, whatever -- most people would describe the route in detail and not shorten it. For example:
To get to the office of the Registrar, enter the Administration building, head left to the second hallway, turn right and go past the Dean's office, and then left at the T-intersection. The office will be on your right.
You could shorten this, but it would assume people know where you're talking about.
Although, as a different example: Here in Southern California there are a lot of intersecting "freeways" (elsewhere called highways or expressways) and many routes to get from one place to another. So if I was directing someone how to get to Los Angeles Airport from Pasadena, I might suggest:
Take the route from the 210 to the 110 to the 10 to the 405 to the 105, and that'll take you right into the airport.
which assumes someone familiar with the freeway system and who knows what freeway numbers I mean, and how they run (generally north-south or east-west). If I was explaining this to someone not from LA, I would probably be more detailed.
(Of course if you look at the map you'll see you can just take the 110 to the 105, but sometimes traffic is a nightmare on the 110 south of downtown. I digress)
I don't know if there is a shortcut for this in other languages, but in English it's common to be "wordy" if that makes your directions more clear.