I read this book over 5 years ago, borrowed from a friend, but I believe it is quite a bit older.

A spaceship finds several planets where advanced civilizations have collapsed fairly suddenly, and where a nearby planet or moon has ruins of large, blocky structures that were never inhabited. Correlating locations and times shows that the Civilization Destroying Force sweeps through the galaxy like a wave front, The space farers gradually realize the ruins were built by a benevolent alien race hoping, in vain, to distract the attention of the destructive force wave from the nearby civilization.

I expect there were several sequels, and would be interested in finding the whole series.