The neighborhood , loosely defined as the area between Walnut , Lombard , Front and 8th streets contains the largest concentration of original 18th and early 19th century architecture of any place in the United States .
The neighborhood , loosely defined as the area between Walnut , Lombard , Front and 8th Streets . 
 It contains the largest concentration of original 18th and early 19th century architecture of any place in the United States .