There are quite a few tours in DC. Ok, there are more than quite a few tours. We have so many tours available to us. But the truth is, most of those tours are geared towards tourists. Or we’ve already taken them. But there is one unique tour in DC that is a great activity for Washingtonians. The Naval Observatory offers one of the most interesting and unknown tours in DC but it’s only offered at night.
The US Naval Observatory is one of the oldest scientific agencies in the country. It's also one of the few pre-1900 astronomical observatories near an urban area. When it was built, it was quite far from the light of the city center.
The primary function of the observatory is to product Positioning, Navigation and Timing insight for the Navy and the Department of Defense. It's home to the "Master Clock" which provides the precise time.
Tours are free to the public. For security purposes, tours must be made in advance and they are only offered at certain times of the year. There are not tours available right now but keep an eye on their website for updates on when tours will be available.