Oh, that obviously went really badly! Fortunately, we have a different experience. We also signed a construction contract without having secured a plot of land in writing, but our situation was significantly different. We are buying the plot from acquaintances who have firmly committed to us and whom we trust (the plot is a gap in a "new development area" from the 60s), and the construction contract includes clauses allowing us to withdraw if we either do not get financing (which is now secured) or if we cannot purchase the plot after all. Our acquaintances kept their word (although in the meantime another interested party had actually inquired) and the notary appointment for the purchase is coming soon. So it is not necessarily wrong to sign the construction contract before the land purchase contract... it very much depends on the circumstances.