Blog · October 14, 2026 · Pennsylvania
The Castle Shannon GIS Map and the county parcel viewer
Most property questions near Mount Oliver start with a parcel lookup.
Main page: Allegheny County, PA GIS & Parcel Viewer (official map link, county facts and neighboring maps).
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When land near Brentwood catches your eye, the Castle Shannon GIS map shows lines, owner names and parcel numbers. What this Castle Shannon guide covers: where that map lives, the fastest ways to search, and the limits worth knowing.
The official viewer behind the Castle Shannon GIS map
Parcel maps here are usually run by the county, not the town, so for Castle Shannon the go-to is the Allegheny County ArcGIS parcel map.
Getting to the right map
Go first to the Allegheny County ArcGIS parcel map; it covers every assessed parcel from Dormont to Bethel Park. If the land is near Bethel Park, type a street address, an owner's name or a parcel number, then pick the result to center the map on it. For a tract near Bethel Park, write down the parcel ID while you have it open; every clerk in the county asks for it first.
Where Castle Shannon fits in
Castle Shannon is part of Allegheny County, Pennsylvania, so its parcels are on the county's map. For a home near Brentwood, the municipality handles things like zoning, permits and utilities for lots inside the boundary, while the county keeps the tax map. Lots just outside the town limits near Whitehall often answers to county rules, not municipal ones.
Recorded documents worth pulling
The map is an index, not the title: recorded deeds, subdivision plats and easements for land near Brentwood sit with the Recorder of Deeds. For a home near Mount Oliver, have ready the book and page listed on the parcel record so staff can find the deed fast.
How land is described here
Tracts outside towns near Dormont are often described by metes and bounds, listing bearings, distances and landmarks. Platted lots around Whitehall refer to a recorded plat, making them easier to find. Copy the legal description from the record for the parcel near Dormont when you talk to a surveyor.
Three ways to find a parcel
Acreage around Mount Oliver might not have a street number, so pan the aerial and click the lot. Out toward Mount Oliver, a parcel ID is the most reliable search, and it's printed on tax bills.
Beyond the parcel lines
Toggling imagery near Green Tree shows roofs, driveways and tree lines next to the parcel edges.
Keeping a record
Print or screenshot the parcel near Green Tree with its ID visible, so you have it when calling an office.
What the map can't tell you
Acreage on the record is a tax-roll number; just a licensed surveyor sets the real lines on land around Dormont. For property near Bethel Park, owner names and values update on a schedule, so a deed recorded last month may not show yet.
Getting answers from the right desk
Questions about value or the owner field for land near Mount Oliver go to the county assessment office, the office behind the parcel record. Zoning, permits and septic questions near Green Tree need the planning or permitting office, depending on whether the land is inside town limits.
Troubleshooting the viewer
If the viewer stalls on a phone near Dormont, switch browsers or turn off pop-up blockers; links occasionally change, and our directory page keeps the current one.
A quick look at the area
Pittsburgh serves as the county seat, home to the main records offices. Other places on the map include Whitehall, Dormont, Brentwood, and Bethel Park, each with its own cluster of lots. About 1,224,825 people live in Allegheny County (Census estimate, 2023) spread over about 730 square miles. Allegheny County was formed in 1788, and some chains of title near Mount Oliver are long. Places such as Allegheny River and Monongahela River help you orient on the aerial around Bethel Park.
Inside the parcel card
Recent sales on nearby lots in Castle Shannon are a useful starting point; an appraiser is the real authority.
Next door to Allegheny County
Allegheny County borders Armstrong County, Beaver County, Butler County, Washington County, and Westmoreland County; every one of them runs a separate parcel map. Ground near Dormont that runs to the line can be split across two assessors' files, so look at the adjacent map before you assume the acreage. For a parcel near Whitehall, our state page lists each bordering county map for Pennsylvania.
Frequently asked
Is the Castle Shannon GIS map free?
Short answer: the Allegheny County ArcGIS parcel map is free and opens without a login, though printing may be limited.
Where else can I find maps of Castle Shannon?
Usually, check the Castle Shannon website or ask city hall, while parcel data usually comes from the county.
How do I find who owns a lot near Bethel Park?
For most people, click the lot near Whitehall to see the owner, or search by address instead.
Can I use the Castle Shannon GIS map for a fence near Green Tree?
Short answer: lines near Green Tree can be off by several feet or more; get a survey before a fence.
Who do I call about a parcel near Dormont?
For land near Brentwood, assessment goes to the county assessment office and deeds to the Recorder of Deeds, while zoning questions go to planning
Open the official Allegheny County, PA parcel map See it in the Platbookmapper directory
Not a survey. County GIS and tax parcel maps are assessment and planning layers. They are not a substitute for a recorded plat, deed, or licensed survey, especially for fences, setbacks, or boundary disputes.