Two different approaches to historic preservation, both of which are now frowned upon by most folks in the field.
Williamsburg is, for the most part, recreations of historical buildings. It was spearheaded by Reverend Dr. W.A.R. Goodwin, who eventually recruited John D. Rockefeller Jr. to bankroll the process. The demolished a lot of buildings (most that were older than 1790), and in some cases took existing buildings down to their foundations, then rebuilt them, and then presented them as originals. Nowadays in historical preservation, "newer" buildings would not be demolished, buildings would not be taken to their foundations/rebuilt/presented as original, and only in very rare cases (and still frowned upon) would former buildings be recreated.
While Independence National Historical Park is a newer creation than is Colonial Williamsburg, it still suffered from outdated preservation procedures. It has a twisted history. The Historic Sites Act of 1935 started the process, and Independence Hall was named a National Historic Site in 1943. During the late '30s, the concept of a mall for 3 blocks north of Independence Hall was conceived. The National Park Service (NPS) didn't like the idea -- they only were interested in a mall 1 block north of the Hall. Backers of the larger idea took it to the PA legislature, which was interested but never fully backed it. Eventually, the city of Philadelphia and the Commonwealth of Pennsylvania agreed to create Independence Mall, and then turn it over to the NPS. They purchased all the buildings in the 3-block area north of the Hall, and demolished all but 1 -- the Free Quaker Meetinghouse. The reason that survived is that it was the only building in the 3 block square that pre-dated 1776, and even it didn't survive unscathed -- it was moved 30 feet to accommodate the widening of 5th Street (one of the boundaries of the present Mall). Included in the buildings that were demolished were the walls of the house owned by Robert Morris that served as the President's house when Philadelphia was the national capitol.
The problem with the Mall approach is that the Pennsylvania State House (now known as Independence Hall) never existed with a 3-block expanse to its north that was mostly devoid of buildings. It was built in an urban area, and as such had buildings across the street, and in the 3-blocks to its north. The area south of Independence Hall was, as is now, mostly free of buildings. Interestingly, the 3-block mall has changed a great deal since the NPS took control of it. The Liberty Bell is now housed in a building on the western side of the 1st block. A visitor's center now exists on the western side of the 2nd block. Lastly, the Constitution Center was built across the majority of the 3rd block of the Mall.
As for recreations, the NPS did build City Tavern a few blocks from Independence Mall in the mid-70s. It was an important building in the historical process -- the initial meeting of the First Continental Congress took place there, before they decided to meet at Carpenters Hall. They also recreated the Graff House (also called the Declaration House) in the mid-70s, which is the boarding house that Thomas Jefferson stayed at during the Second Continental Congress, and where he wrote the initial draft of the Declaration of Independence. In time, the NPS did adopt more modern historical preservation techniques, which can be seen at Franklin Court (where Ben Franklin lived), or at the President's House Memorial, which opened in 2010 on Independence Mall.
As for dawg's comment about the building that houses the Liberty Bell, it's better looking than its previous building (which was built for the Bicentennial), and far more accommodating for tourists than where the Liberty Bell was stationed for decades -- at the bottom of the stairwell of the Independence Hall tower. I don't have a problem with the current building that houses the Liberty Bell. It's big enough to accommodate the huge number of tourists that visit it, and it affords one a view of Independence Hall while looking at the bell.
