How many days is it appropriate to travel to Philadelphia?

how many days does it take to travel to Philadelphia? I think it will take at least three days. I stayed in Philadelphia for three days when I went to the tour group in Nami before, but I was not in a hurry. I can visit the National Independent Historical Park in Philadelphia, look up at the Independence Palace, a historical relic building, and take a double-decker bus in Philadelphia to learn more about the birthplace of the historical cradle of the eastern United States.