If the case is as mentioned in the question, the husband is not entitled to take the money he spent on the construction of two apartments, as long as there is no definite proof that the two apartments belong to him or that his wife is their fictitious owner. Her ownership is established because the apartments were located on her land and she died while they were still on her property. This fact cannot be changed except by stronger [evidence to the contrary].

Merely paying for the cost of construction involves unlimited possibilities which may include:

- The cost of construction was in return for a debt the husband owed his wife.
- It constituted her dowry or its deferred portion.
- It is a gift the husband made to his wife which she accepted and received while she was alive.

In addition to the above, there may be other rational possibilities. It is possible that the two apartments do in fact belong to the husband. But since the probabilities are equally plausible, we resort to the fact that the apartments belong to the wife and not the husband until proven otherwise.
Allah the Almighty knows best.