The things that decide what a house here is likely to need: geology, water, flood exposure, housing eras, and environmental history.
Traprock ridges and the ground between them
East Rock and West Rock are basalt ridges standing above sedimentary lowlands, and the neighborhoods on their flanks sit on shallow, hard ledge. Ledge redirects groundwater rather than absorbing it, which is why basements at the base of a slope behave differently from basements two streets away.
Three rivers and a harbor
The Mill, Quinnipiac, and West Rivers all reach the harbor through the city, and the low ground along them, Fair Haven, the Quinnipiac Meadows, parts of the Hill, has a flood history. Add tidal influence at the harbor and Morris Cove, and flood zone status becomes a per-address question worth answering early.
Old drain and sewer laterals
Housing this old is connected to the street by laterals that are frequently as old as the house. Clay tile and cast iron lines, tree roots, bellies, and partial collapses are common enough in the older neighborhoods to be worth planning for. A visual inspection reports what it can see; a camera scope is the honest way to answer the question definitively on a hundred-year-old lateral.
The three-family building type
Built largely between the 1890s and the 1930s, usually balloon-framed, usually with a single original heating plant later split into three, often with porches stacked three high on the rear elevation. Egress, unit separation, individual utilities, added kitchens and bathrooms, and the condition of those rear porches are the recurring themes.
Radon: EPA Zone 1
New Haven County is Zone 1, the EPA’s highest-potential category, on a predicted county-wide average above 4 pCi/L. A county prediction is not a house measurement, and city basements vary widely, testing is the only way to know.
Lead and older finishes
The overwhelming majority of housing here predates 1978. Lead paint is a normal condition of the stock rather than an anomaly, and it is managed rather than feared, but a buyer with young children should go in knowing, especially where painted windows and porches are original.