Mochi Hidden America

Historic places, explained

Free · Designed for iPad. Not verified for macOS.

90,180 places on the National Register, every one of them on your phone and offline. Point your camera at a building and find out what happened there. Every place on the National Register of Historic Places — 90,180 of them — on your phone, and the map works with no signal at all. Hidden America is an atlas of the listed places around you: the buildings, districts, ships, battlefields and archaeological sites the United States decided were worth keeping. It ships with the whole Register inside it, so browsing, searching and the map all work in aeroplane mode. Add your own Anthropic API key and it becomes something else — a guide that reads a place's federal record and the archival photographs matched to it, and tells you what actually happened there. THE WHOLE REGISTER, ON THE DEVICE Both public layers of the National Park Service's data: individual listings and mapped historic districts, 90,180 places including 2,429 National Historic Landmarks. Nothing is fetched to draw the map or run a search. BROWSE WHEN THE MAP IS EMPTY Most of the country is a long way from the nearest listed place, so the app opens on a list rather than a blank map. State, then city, then place — with counts. New York alone has 6,099. FIND IT BY NAME OR BY STREET Instant search across every listing name and street address in the country, offline. WHY A PLACE MATTERS, WITH ITS SOURCES The guide reads the listing's record and the photographs matched to it, then writes the history. Documented fact, inference and open questions are kept visually apart, and every claim points back at the source it came from — the nomination file at the National Archives, or the item at the Library of Congress. SIX WAYS TO LOOK AT ONE BUILDING • What the nomination says • What happened there • Who designed and built it • Whose perspective the record left out • How the neighbourhood changed • What primary sources survive THEN & NOW Put a historical photograph and your camera's live view on one slider, line them up, and have the differences read back to you — what is gone, what survives, what to look for. POINT THE CAMERA AT A BUILDING The app takes what it can see, the direction you are facing and the listings lying that way, and tells you which one it probably is — with a stated confidence, and a willingness to say it is none of them. A PASSPORT OF WHAT YOU LEARNED Places visited, architectural styles met, eras walked through, and the one thing worth remembering from each. WHAT ISN'T HERE No ads. No account, no sign-up, no password. No analytics, no crash reporting and no tracking of any kind — the app has no server of ours to talk to. ABOUT THE GUIDE The written history, Then & Now and building identification are generated by Claude and run on your own Anthropic API key, which you add in Settings and which never leaves your device except to reach Anthropic. There is no subscription. Everything else works with no key at all. ABOUT THE DATA The National Register is a United States register, so the app covers the fifty states and the territories and nowhere else. Listings come from the National Park Service and exclude the restricted and sensitive archaeological sites the Service withholds. Photographs come from the Library of Congress, where rights vary item by item — every one links back to its page.

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The developer, PTK Ventures LLC, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .

  • Data Not Linked to You

    The following data may be collected but it is not linked to your identity:

    • Location
    • User Content
    • Identifiers
    • Usage Data
    • Diagnostics

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Information

Seller
  • PTK Ventures LLC
Size
  • 12 MB
Category
  • Travel
Compatibility
Requires iOS 18.0 or later.
  • iPhone
    Requires iOS 18.0 or later.
  • iPad
    Requires iPadOS 18.0 or later.
  • Mac
    Requires macOS 15.0 or later and a Mac with Apple M1 chip or later.
  • Apple Vision
    Requires visionOS 2.0 or later.
Languages
  • English
Age Rating
4+
Copyright
  • © 2026 PTK Ventures LLC
  • Developer Website
  • Privacy Policy

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