The link between the outlying settlements and Philadelphia is apparent in this former jail that in its overall proportions and central cupola is based on Robert Smith's pre-Revolution Walnut Street Prison. The crowning feature, a giant weathervane in the form of a key, is an early intimation of the expression of purpose that would characterize nineteenth-century architecture. In most counties a jail was among the first structures to be built and was particularly important as the rule of law was extended into the unruly Scots-Irish frontier. The first floor of the jail contained the jailer's quarters, which are trimmed with the type of carving characteristic of German Pennsylvania near Lancaster. The present cornice is Victorian.