It is hard to explain the feeling that comes over Boston every time the fourth of July comes around. There is an energy in the air that is fed by the thousands of tourists and historical re-enactments and displays that pepper the town. Nowhere is this feeling more evident than the Charlestown Navy Yard, where the USS Constitution is docked. Not only is the USS Constitution decked out with flags and patriotic decorations, but there are also typically several other Navy ships that visit the yard for the weekend.
The Navy Yard is accessible through many of the bus tours that circle Boston and also through the ferry with service from Rowes Wharf (close to Faneuil Hall). A footbridge and harbor-side walking path can be found that connect North Station with the Navy Yard area, if you know where to look for them (behind North Station--- over the canal locks that separate the Charles River from Boston Harbor).
In 2010, the World War II Destroyer USS Cassin Young was docked in the Navy Yard for the Fourth of July festivities. Another Navy ship was also docked in the yard, but the USS Cassin Young was the only one that was open to public tours. It was interesting to walk around the deck of the Destroyer and view the gun turrets and torpedo launchers. It was also interesting to see the very small dining and sick-bay facilities which make one wonder how anyone could've survived their stay on the vessel back in the day. The main deck was the only one open for public viewing, but I saw several park rangers give guided tours of the lower boiler rooms and quarters to a few people upon request.
The USS Constitution was very crowded on the weekend of the Fourth. Navy personnel keep the line moving smoothly to get aboard the ship, but it probably took a half-an-hour more than usual to get through the line. Boarding the USS Constitution is difficult to do on July 4th itself, since it is engaged in its annual "turnaround cruise" for the better part of the day. But seeing the ship sailing in the harbor is still a sight to see in itself; best viewed from another boat. As always, all the attractions in the Navy Yard including the Constitution and the USS Cassin Young were free to partake in.
I would highly recommend visiting the Navy Yard in Charlestown if you are looking for a truly patriotic experience on the Fourth of July. Few places offer this kind of spirit and historical experience in the same package. The flags and patriotic decorations are typically only on display during this time of year, so make for the perfect photo opportunity to remember your summer Boston travels.