I took this photo in an 1840s-1850s residential neighborhood in St. Louis. A house once stood here, torn down long ago. More recently, the lot was paved over with asphalt. The fill of the cellar associated with house gradually compacted and slumped, causing depressions to form in the asphalt above. Now, when it rains, pre-Civil War archaeological features are plainly visible. Imagine what may lie beneath.