Carpenters' Hall (1773) was the guildhall for -- guess who? -- carpenters. At the time, the city could use plenty of carpenters, since 18th-century Philadelphia was the fastest-growing urban area in all the Colonies and perhaps in the British Empire outside of London. Robert Smith, a Scottish member of the Carpenters' Company, designed the building (like most carpenters, he did architecture and contracting as well). He also designed the steeple of Christ Church, with the same subdued Georgian lines. The edifice is made of Flemish Bond brick in a checkerboard pattern, with stone windowsills, superb woodwork, and a cupola that resembles a saltshaker.
You'll be surprised at how small Carpenters' Hall is given the great events that transpired here. In 1774, the normal governmental channels to convey Colonial complaints to the Crown were felt inadequate, and a popular Committee of Correspondence debated in Carpenters' Hall. The more radical delegates, led by Patrick Henry, had already expressed treasonous wishes for independence, but most wanted to exhaust possibilities of bettering their relationship with the Crown first.
What's here now isn't much -- an exhibit of Colonial building methods, some portraits, and Windsor chairs that seated the First Continental Congress. If some details seem to be from a later period, you're right: The fanlights above the north and south doors date from the 1790s, and the gilding dates from 1857. Hours are short because the Carpenters' Company still maintains the hall.