2 different boundaries to the outdoor area

Hello dear forum members,

my wife and I are considering building a house on her parents' property. I looked up the land value of the plot online. Here, roughly half of the garden (from the line seen on the right) is building land and the other half is grassland (left of the boundary). It is exactly the kind of place where a house would fit perfectly (adapted to the neighborhood, connection to the street for the fire department is available).

However, at the building authority, the boundary to the outer area is located significantly further to the right, so the entire area is classified as grassland.

What takes precedence here? The land value determined online or the boundary to the outer area from the authority?

And am I right in assuming that the land value generally reflects the boundary between building and grassland or inner and outer area?

Does someone perhaps need to take a look on site? An architect or something similar?

I apologize in advance if anything is unclear or if some information is missing, but I am an absolute beginner when it comes to house building.

Thank you and best regards

Edit: The entire property, including the entire green area, is fully developed!

Right, left... I don't see the attachment. You probably forgot it ;)

Is the property being newly settled?

Is there even a suitable building window for your project?

Oops, Edit: not "eingessen" :rolleyes: but "eingemessen." Autocorrect ;)

Good evening,

What has priority here? The online determined standard land value or the boundary to the outer area from the office.

Before you get caught up in any lines or values: is hinterland development allowed? Is there development in the second row in the immediate neighborhood? What does the building planning office think of your idea?

Rhenish greetings from on the road

Good evening,

Before you get lost in any measurements or values: is Hinterland development allowed? Is there development in the second row directly next door? What does the building planning office think of your idea?

Rhine greetings from the road

Hello

First of all, thanks for your answers.

Hinterland development is allowed or rather must be allowed. There are at least 4-5 houses in the second row in the immediate neighborhood. The building office... yeah, the good building office. What can I say, we wanted to inquire about how exactly it works, but were immediately met with rudeness and directly rejected. With the words, and I quote: THAT IS NOT POSSIBLE!

: What do you mean by newly surveyed? And what am I allowed to understand by suitable building envelope?

I apologize once again but I am an absolute layman when it comes to house building!