When did you find him? If its only been a day, don't you think its a little soon to be rehoming him already?
If the place is closed today, then call tomorrow, put out found adds around the place and on Craigslist and at vets offices. If you absolutely cannot keep him, then take him to the shelter so that there is at least a chance of the owners finding him.
We are defined not only by what we create, but by what we refuse to destroy.