It is a fascinating museum piece and a critical historical milestone in browser evolution, but using it on the modern web is asking for compromise.

You can find the official, unmodified installer here: https://ftp.mozilla.org/pub/firefox/releases/52.9.0esr/

Select your operating system:

For the millions of machines still running Windows XP (e.g., point-of-sale systems, industrial control panels, museum kiosks, and classic gaming rigs), Firefox 52.9.0 ESR represents the final secure gateway to the modern web. After this version, no further Firefox updates—security or otherwise—would work on those systems.

: It is the absolute last release for XP (SP2/SP3) and Vista. Legacy Extensions : This version still supports XUL-based "Legacy" extensions