Tours are only offered on two Mondays a month and are frequently booked solid. We got lucky enough to recheck the website to find they were once again accepting new reservations and were offered spots on an upcoming tour when we were going to be in D.C., not bad considering only about 35 people will get passes. We arrived shortly after 7:30 pm, the security screening begins at 8:00, you are at the property where the Vice President of the United States lives! The tour proceeded with our guide giving a terrific overview of the history of the Naval Observatory as time keeper for our nation during its early days in Washington D.C. and the various methodologies employed over the years leading to today. From this we were led through the observatory grounds to the old telescope still in use. Inside the observatory the group was offered the chance to look at Jupiter and two of its moons. Next stop was the USNO Library featuring one of the worlds greatest collections of books about astronomy and mathmatics. We never did get to see the VP but had a great time spending our evening at this rarely toured D.C. icon.