This is a better book than "The Genesis Quest" - for one thing, there is no human conflict, which is not as interesting as the conflict in this book.
After a journey of 37 million years from the Whirlpool Galaxy to our own, humans find an engineering project on an even larger scale than Larry Niven's Ringworld, and more complex. The Author also explains how the project was carried out, which Niven does not do. They also discover some interesting species there.
There are several scientific errors, and I noticed two problems with the physics which would prevent the project from working as proposed, but I can live with that, and there are plenty of interesting ideas and surprises to keep you entertained.