On the corner of Second and Merchant, almost directly across Merchant street from the Parfait Dufour house. Most of the records I found say it was built in 1818 or thereabouts, although the sign on the building says 1790. Parfait Dufour originally owned the lot. The building was sold to Lewis Linn in 1831 — his house is just west of this building, with an empty lot in between.
This building is made of cut stone, the surface of which is very smooth and flat, unlike the textured surfaces of the stone buildings in Mineral Point. The smooth surface makes it look a lot like cement blocks.
More information about the building at Waymarking.