§ I · The two-map problem: historic designation
Nearly every historic-district misunderstanding comes from conflating two different maps. The National Register is federal recognition — an honor with rehabilitation-tax-incentive upside, and for private work with private money, essentially no restriction by itself. The local historic zoning overlay is the instrument with teeth: a municipal ordinance with a design-review commission that approves exterior work before the building permit. The maps only sometimes coincide — Register-listed neighborhoods with no overlay, overlaid blocks never listed, both-in-part with mismatched boundaries. The developer's read: a parcel inside a Register district gains one more situational hook — projects involving federal permits, funds, or licenses trigger historic-preservation review of effects — which matters exactly when your project needs, say, a Corps permit. Check both maps before the pro forma: the Register's public spatial data for the listing, the city for the overlay and its guidelines. Design review isn't a wall; unbudgeted design review is.
§ II · Protected ground: the family cemetery
Tennessee buried at home for two centuries, and the plots persist — thousands mapped in federal and state records, present on far more old acreage than any buyer expects, and frequently invisible from the road: a fenced quarter-acre in a back pasture, a cedar grove with six stones. Under Tennessee law they are protected ground: building over, moving, or disturbing a burial ground requires a chancery-court process with notice to descendants — a proceeding whose timeline and outcome no closing date, and no site plan, controls. The developer's read: a mapped cemetery on target acreage isn't a deal-killer — it's a fixed feature, designed around like a stream buffer, with access preserved (descendants hold visitation rights). The plan that treats it as parkland edge works; the plan that needs its footprint doesn't. Find it before the yield math, not after. And the standing archaeology boundary: sensitive site locations are confidential by law and absent from public data by design — for ground near water or known settlement history, a qualified archaeologist's records check (they can access the state files no public screen can) is the professional early step.
§ III · Air & ground rights-of-way: noise, corridors, easements
Aviation noise runs by the nearest airport, not the famous one. A site's DNL exposure — and the disclosure, financing, and use implications that follow for noise-sensitive development — depends on which of Tennessee's commercial airports actually owns its sky: BNA, Memphis, Knoxville, Chattanooga, Tri-Cities. Memphis deserves its own sentence: a global cargo hub with heavy nighttime operations, which makes its noise question one the daytime site visit structurally cannot answer. Transmission corridors and mapped easements are the ground-level equivalent: a high-voltage line across the back of the acreage is a permanent setback, a crane-operations constraint, and an appraisal conversation — and mapped corridors are checkable from public spatial data before the survey. (Recorded deed easements remain title-search territory; the maps tell you where to make the title company look hard.) Rail, landfill, and heavy-industrial adjacency round out the class: none score as hazards on your parcel; all price into what you can build next to them.
§ IV · The bottom line
Constraints differ from contamination in one merciful way: they're certain. No sampling, no plumes, no probabilities — a district boundary, a protected plot, a mapped corridor either touches your parcel or it doesn't, and every one is readable from public records before the LOI. The site plans that die at review boards and chancery courts were drawn before anyone read the constraint layer; the ones that sail were drawn after. Read first, draw second — it's the cheapest engineering decision on any project.