First look at feng shui. Ancient and modern princes were buried in a treasure trove of geomantic omen, such as Mangshan Mountain in Luoyang, facing the Yellow River and backed by mountains.
Second, read ancient books. Many ancient books, unofficial history, can find clues about the imperial tombs.
Third, listening to legends, many legends handed down by the older generation are not necessarily groundless.
Fourth, listen to the wind and thunder (the highest realm).