# Henge days for a building

This page computes its dates in the browser when it is opened, and keeps a summary for 60 days afterwards so that links to it can show them. Nobody has opened this one recently, so there is nothing stored to tell yet. Open https://hengedays.com/at/42.64797,-71.30729?q=Boott+Cotton+Mills%2C+115+John+Street%2C+Lowell%2C+MA in a browser, then ask again.

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Every date and time is computed from a building outline in OpenStreetMap and the position of the sun, never checked on the ground. Hills, trees and other buildings can block a low sun. Treat each date as a plan to confirm. See https://hengedays.com/terms.md.