CONFIRMEDDate confidence: CONFIRMEDStated as firmHow firmly the source words the date: confirmed, scheduled, estimated, delayed or unverified.Show all CONFIRMED pins90% CONFIDENCEOverall confidence: 90%How well the pin's source and references back up its dates.Weighted average of how firmly 3 references, the source included, support the pin's start and end times; a reference counts half as much for every 180 days older than the newestShow all pins at 75% confidence or better2.2 years ago
Happened as dated, per the source[1]: "completion of excavation work for the Long-Baseline Neutrino Facility".Crews finished carving three enormous caverns a mile beneath a former South Dakota gold mine to house the Deep Underground Neutrino Experiment.