In which U.S. city will you find a post office without a ZIP code?

The B. Free Franklin Post Office & Museum is located in the historic Old City section of Philadelphia, PA. Housed in the three-story row house where Benjamin Franklin lived from 1737-1753, it is the only Colonial-themed post office operated by the United States Postal Service. Employees dress in period costumes and use quill and ink rather than ballpoint pens.

B. Free Franklin is a living portrayal of a bygone Colonial lifestyle, and the only active post office in the United States that does not have a ZIP code or fly the American flag. In keeping with the Colonial theme, it doesn't have a ZIP code or fly a U.S. flag because neither existed in 1775, when Benjamin Franklin was appointed postmaster general.

The post office gets its name from Franklin's signature. In Colonial times, the common practice was for the sender’s signature to be put on the outside of a letter. As the first US Postmaster General, the founding father signed his envelopes "B. Free Franklin", as a form of protest against British rule.

The postmark "B. Free Franklin" is still used to cancel stamps. Visitors are able to purchase cancelled stamps as souvenirs. A museum on the second floor features displays of postal history and memorabilia.