There are small mausoleums scattered throughout the cemetery where I walk. Many of them harbor stained glass windows, windows which almost no one sees. And why is that the case, that almost no one sees them?
For one thing, not that many people spend time at the cemetery. And those who do tend to be walking or running, or visiting the graves of those they love, or perhaps stopping in to see the Garfield Monument. They aren't pausing to do more than glance at the smaller buildings.
And the windows are usually on the back side, often covered with protective grating. Even if someone were inclined to walk around to the back, she wouldn't see much. You have to walk up to the front door (all of them locked) and peer in, hoping that the sun will illuminate the window from the back. If you and the sun both co-operate, you may be rewarded with a view of a small, hidden treasure.