The best way to describe this style is probably “Baroque”: it’s a splendid half-underground mausoleum, of the type usually called a “burial vault” in the days when such things were built. It’s the only one in the Chartiers Cemetery, which was founded in 1861.
The front bears the date 1874, which suggests that the vault was built originally for David C. Steen, who died at the age of 20 or 21 in that year. An Emma M. Lappe Steen died the next year, also at the age of 20 or 21; did a young widow never recover from her loss? In fact, the mere dates tell us a good deal about the appalling mortality even among the well-to-do in the nineteenth and early twentieth centuries. In a list of eleven names, four lived past the age of thirty.