There’s also Charles Sheffield’s Heritage Universe series, most of which centers around people exploring huge artifacts left behind by a vanished alien race.
And I came in here to mention Jack McDevitt’s books but I see that Reality Chuck beat me to it, so I’ll just second his recommendation even though I haven’t finished the series yet (I just discovered it and am only up to Omega). It’s interstellar archaeology from the Indiana Jones school of archaeology though (lots of improbable action and adventure, not that there is anything wrong with that).
Probably half or more of the stuff written by Andre Norton involves lost civilizations at some point. The Witch World books are full of them, various races of “Forerunners” in her Free Traders books ( such as Forerunner, The Zero Stone, Exiles of the Stars and Sargasso of Space ); the Ift in Judgement on Janus, whoever made the spooky ruins in Catseye.
The Trillium books by Marion Zimmer Bradley, Julian May and Andre Norton have a lost civilization as a backdrop ( and source of high-tech/magic goodies ) to a fantasy style culture.
Tanith Lee’s Birthgrave has a main character who is the amnesiac lone survivor of a dead civilization, woken from a sleep of centuries.
A lost civilization is a major plot point of Barbara Hambly’s The Darwath Trilogy, and a different ( nonhuman ) one in one of the sequels, The Mother of Winter.
Another excellent series was the “Giants” series by James. P. Hogan. The first book in the series, “Inherit the Stars” starts with the discovery of a 40,000 year old corpse in a spacesuit on the Moon. I’ll let you read the rest for yourself.
One of the sub-plots of Poul Anderson’s Fire Time involves creatures who may or may not be descendants of a lost civilization, and one of the artifacts of that civilization.
Ditto, so I’ll “third” that. McDevitt has two different series of books (the “Academy / Priscilla “Hutch” Hutchins” series and the “Alex Benedict” series) which both deal with xeno-archaeology and far future archaeology.
Since McDevitt seem’s well represented I’ll add a nomination for some of the works of Mike Resnick. A couple of his books that I’ve enjoyed, and that fit the OP are (lifting from his wiki page): The Dark Lady (an alien art dealer investigates a mysterious woman who appears in paintings created thousands of years apart), and *Ivory *(the search for a pair of tusks that covers thousands of years and dozens of worlds).
Tad Williams’ Memory, Sorrow, and Thorn books, starting with The Dragonbone Chair features several lost or declining civilizations, the main one being that of the Sithi who were mostly driven out of the lands where the main character, Simon, lived at the beginning of the book. Like Tolkein’s Middle Earth, there’s a sense of history and age to the world. Besides inevitable parallels to be drawn with Tolkein, Williams manages to work in medieval literature references (like Prester John) and history, and includes many cultures that are a lot different from your standard Celtic/European medieval fantasy setting.