While renovating the apartment, a bag of money was found sealed into one of the walls. The money was counted to the grand old sum of 150,000nis. 

There was no mention of the money in the dead brother's will, and the question is now who is the rightful owner of the money. Does the sister inherit it from the brother? Was it hers as owner of the apartment? Is it the avreich's who bought the apartment, which is sold "as is"? maybe the owner of the money had given up on ever finding it, not knowing it was sealed into a wall?  Maybe it has to be returned to her because she could not have given up hope of the money not even knowing it was there? 

The avreich went to the dayan Rav Yehuda Silman to ask what to do with the money.

Rav Silman paskened that he has to return the money to the woman, the previous owner of the house as she did not know about the money when she sold the apartment.

The avreich wated to turn the returning of the money into a kiddush hashem event so he asked the woman to come down to the rabbi's house and held an event there to return the money, inviting several friends. The woman was very emotional hearing the story and also realizing she had inherited money from her brother. Rabbi Silman conducted a "lachayim" with the participants and blessed the avreich with an overflow of blessings in his new house and that his children should follow the path of the Torah.

source: Behadrei

What would you do? I hope I would do the right thing, ask and return it accordingly if that would be the answer given. I wonder if I might not even ask and come up with a logical sevara of why it is is mine or hefker and does not need to be returned.