As America prepares to celebrate the country’s 250th birthday, NBC News takes a close-up look at one of the nation’s most iconic landmarks and the person who preserves its history. Tom Llamas introduces us to archaeologist and curator Debbie Miller, the guardian of the Liberty Bell.  For more context and news coverage of the most important stories of our day, click here: nbcnews.com » Subscribe to NBC News: nbcnews.to/SubscribeToNBC » Subscribe to Here's the Scoop podcast: nbcnews.com/heres-the-scoop-daily-podcast » NBC News App: apps.nbcnews.com/mobile » Breaking News Alerts: link.nbcnews.com/join/5cj/breaking-news-signup?cid=sm_npd_nn_yt_bn-clip_190621 » Visit NBCNews.Com: nbcnews.to/ReadNBC » Find NBC News on Facebook: nbcnews.to/LikeNBC » Follow NBC News on Twitter: nbcnews.to/FollowNBC » Follow NBC News on Instagram: nbcnews.to/InstaNBC #independenceday #LibertyBell #philadelphia