I might be confusing two books, but here goes.
The book is about the infamous face on Mars. We find that it is a marker to something underground, but cannot open it as the ways/combination locks to open it are musical. They bring in a musician and he gets deeper and deeper inside until they find that they have activated it.
Now I believe the ending is that inside are these machines building a space machine and they need a nuclear power source and they take it from the gov that was going to blow it up as they could not control it. Sadly the machines building the rocket are not smart enough to know that the aliens that were waiting for a civilization smart enough to have nuclear power died in their crypts long ago, so the ship launches full of dead bodies.