Property on a slope, is the purchase worthwhile?

As long as you do not build directly at the edge where the 3-meter slope is and leave the slope there natural, it does not necessarily have to be retained.
I would have the soil investigated. So that the parking lot was not poorly filled by excavation.

It all looks like filled terrain. The slope runs straight as an arrow, the tree is buried in the ground up to the branching. A soil survey is indispensable here.

Good morning :)
First of all, thank you very much for your numerous and really helpful answers. We will definitely ask the owner whether the land has been filled. Since he owns the two apartment buildings, he might know.
Otherwise, we definitely have the soil survey on our radar.
We were also there again yesterday, checked the slope towards the money, and took photos. Maybe it is easier to see now.
My husband also corrected me and said that there are no single-family houses below, but smaller garden sheds.

According to the owner, the preliminary building permit should also be available next week.

That looks like leftover material from the filled and leveled area for the apartment building, soil survey and no basement close to the slope, as the 3m slope could collapse during earthworks. Maybe you can fill the slope more gently with your excavation.

the two multifamily houses

... look to me more like four eightfamily houses. That someone with so much money / creditworthiness as a builder lets a neighboring little plot lie fallow for so long (the residential complex looks at least sixty years old) smells to me several miles against the wind of good reasons.

Grandchild property and now [Erbengemeinschaft]?

Good evening :)

Thank you very much for your numerous responses.
Unfortunately, I still do not know the background of the property. It will probably be difficult to find out anyway. The current owner is a housing company that manages its residential and commercial properties. The main business areas include the purchase of residential properties, the management of its own housing stock, and the renovation of its own and partly also third-party residential complexes. In recent years, the company has acquired and developed several apartments.

Today we received a call from the owner informing us that the building preliminary approval is now available. So far, that looks quite good. A single-family house may be built and fits into the surrounding development.
However, one clause somewhat irritates us. The notes say the following:
“According to information available at the office, the groundwater level for the location is between 5 and 10 m. Layer water in the upper soil horizons cannot be ruled out. To determine the exact distance, it is recommended to carry out a geotechnical report, within the framework of which the permeability of the soil in connection with rainwater infiltration could also be determined.”

What does that mean specifically? We want to build without a basement.

We would like to have a soil report prepared before purchase. However, there are now so many interested parties that the listing has been deactivated and they now want to switch to a bidding process.
I think that the more interested parties there are, the worse the chances that the owner will agree to a prior report. It is always difficult because naturally one does not want to buy a pig in a poke...