The Lancaster County Jail was designed by Robert Mills and built in 1823. The building was designated a national historic landmark in 1973 due to its connection to Robert Mills, who is recognized as the first American-born architect, and who is most famously known for designing the Washington Monument.

The building incorporates several design features that are linked to jail reforms intended to improve living conditions for both prisoners and guards. A few of these changes included separate living quarters for the inmates and guards, separating debtors from other inmates, and improving airflow into the building to name a few.

The facility is beautifully preserved and can be viewed from Gay Street in Lancaster.