Ft. Sumter located in Charleston Harbor, SC has four Civil War era flags. From left to right: 33 US Star Flag, First National Flag, Second National Flag, and the 35 Star Flag that flew over the fort during the civil war.
Current United States flag flies at the focal point of the Charleston Harbor. I had the opportunity to participate in the raising of the flag with many other tourists. It was a memorable experience.
National Constitution Center in Philadelphia, PA has a display of every state flag in the United States. It is quite a colorful display.