So around WOB I see BRW of ~ 200€/m2 ±100€. With 1200m2 that is 240K€. When guessing further (thanks for reliably providing information), I assume a ground lease of 100 years, starting with the construction of the house, so a remaining term of 70 years and thus a multiplier of 29.12, at the previously mentioned 3% property yield. This results in a market value of the hereditary building right of about 160K€. If the ground floor has 110sqm, I now assume a generous gross floor area (GFA) of 350 m2 (note, GFA is not living space!). According to the cost approach, this results in a market value (2020) of the building of 350m2 * 877€/m2 * 130% = about 400K€. From this, the depreciation must be deducted. For simplicity and rough numbers now linearly (age 30 years, total useful life 100 years) = 30%. That leaves a building value of 280K€. Market value land + building thus comes to (with the assumed data) 440K€. From this must be deducted the value of the right of residence (roughly estimated before at 150K€) and thus a calculated value of 290K€ (all figures rather generous, thus calculated per SELLER). So the owner is not so wrong after all... my gut feeling did deceive me! I had never dealt with market values of hereditary building rights. Here, with the large plot and 3% property yield, there is a "should" of 7200€/year compared to only 1800€ ground lease. This significant difference makes the hereditary building right so "valuable" here.