The festivities on the 4th take place on the Esplanade, which is along Storrow Drive. The renowned Boston Pops play the 1812 Overture in the Hatch Shell Memorial, which is at the end of the esplanade closest to downtown. It's not too far from Copley and the Commons, and one can easily walk from many of the hotels to the esplanade and back. The Esplanade gets very crowded on the 4th, and it's hard to actually see the Pops, but they have speakers and large TV screens set up along the grass so revelers are able to hear the music and watch the screens.

Past performers on the 4th have included LeAnne Rhimes and the Mormon Tabernacle Choir one year and David Lee Roth another.  It is recommended to get there early in the day, about noon, and just sit and picnic all day (take along blankets, folding chairs, and food and drinks) to make sure one has a good spot and enough room. There's usually music playing in the speakers and lots of people around, vendors set up, etc. (As a tip, they'll have port-a-potties set up along the esplanade, but if you walk over to the Commons there's a Starbucks there and I've used their facilities on the 4th to avoid having to go in one of the port-a-potties.) The fireworks are set off from barges on the Charles (the Esplanade is a strip of grass that runs between the Charles and Storrow Drive), and one has an excellent view from the grass (just make sure to pick a spot that isn't behind trees).  The city in past years has closed parts of Storrow so people actually walk to and from the esplanade right down the middle of the road.

"Boston is a wonderful place to spend the 4th."  

** Note:  The original information for this thread came from the following forum thread:

 Added July 2012:

The most direct route to the Hatch shell area is from the Green Line Arlington T Station. Walk north to the pedestrian bridge. Another choice is to go north from theCopley T station, and cross the road and the footbridge to the park along the water.  You must arrive before noon to get a place inside the "oval" to see the concert. You get a wristband and can come and go but be back around 6 as it gets crazy. You can find a place along the park near the sound towers and TV screens but get your spot early!  You can put up a sun screen or umbrellas during the day but must take them down for the evening. Concerts generally start 8-8:30pm depending on the TV schedule.  The playing of the 1812 Overture is an annual tradition, with live cannon fire. Fireworks are generally late - they were 10:30pm in 2012 and delayed by a storm to 11:00pm that time.  You cannot see the fireworks easily from inside the oval.  Use the park areas along the water and ger between the trees for the best fireworks in America.

There is also a rehearsal concert on the Boston side For July 3 as above - no fireworks but all the same rules, and a bit less crowded. You get get there much later for this - 5pm will still get you a good spot in the park in front of a jumbo TV screen.

You can also see the fireworks July 4 on the Cambridge side.  Take the red line T to the Kendall station and walk sound 2 blocks. Stop for food and drinks at the Au Bon Pain or Deli if needed (and there is a Starbucks inside the Marriott).  All drinks at vendors are $3! So get your drinks before you arrive. The streets get blocked by 5pm and it becomes a street party with many food vendors, and like the Boston side there are TVs and sound towers to see and listen to the concern.People stake out places along the river starting at 9am, but you can arrive as late as 5pm and sit behind one of those for a great potential view (mind the trees when you pick your space, you need to look up.)   

Leaving by T is a madhouse, but patience will prevail and you will get on. We parked at Alewife garage, the end of the red line.  It is possible to drive in and park in the garages/lots around Kendall Square too.  What to bring:  Cooler with drinks, folding chairs, blanket, food or money, umbrellas or a sun shade, lots of patience.