Turning Point by Alfred Coppel, Jr., Science Fiction, Fantasy

The man is rare who will give his life for what is merely the lesser of two evils. Merrick's decision was even tougher: to save human beings at the expense of humanity, or vice versa?

This, then, was the Creche, Anno Domini 2500. A great, mile-square blind cube topping a ragged mountain; bare escarpments falling away to a turbulent sea. For five centuries the Creche had stood so, and the Androids had come forth in an unending stream to labor for Man, the Master.