My grandfather gave me a piece of land. The deed of gift contains an inalienability clause valid until his death. I need to borrow money from a bank. Can the latter register a mortgage on my land?

Yes. If the inalienability clause has the effect of prohibiting you from selling or giving away the property you have received, it is always possible for your creditors to take out a mortgage registration on the property given (Civ. 1e, Oct. 9, 1985, n°84-13.306 concerning a judicial mortgage and Civ. 1e, June 25, 1980, concerning a legal mortgage). However, if the clause applies, the property given cannot be seized (Civ. 1e, 8 Feb. 2000, n°97-20.727).