Official Site: https://www.nps.gov/thko/index.htm
Wikipedia: https://en.wikipedia.org/wiki/Thaddeus_Kosciuszko_National_Memorial
The National Memorial was authorized on October 21, 1972. It is administered under Independence National Historical Park but is counted as a separate unit of the National Park System. At 0.02 acres (0.0081 ha) 0.02 acre (80 m²), the memorial is America's smallest unit of the National Park System.
The site is currently open for touring, Saturday and Sunday, from 12:00 noon to 4:00 p.m. No fees, tickets, or reservations are required to visit this site.
8. Thaddeus Kościuszko National Memorial, Pennsylvania
Number of visitors in 2018: 2,077
The memorial honoring freedom fighter and engineer Thaddeus (aka Tadeusz) Kościuszko may be the smallest national park site in the country, but it preserves epic tales of war and freedom in its .02 acres. Polish-born Kościuszko helped American colonists win their independence from the British in the Revolutionary War by meticulously designing and fortifying military defenses. After the war, Kościuszko returned to Poland and led a failed uprising in 1794, attempting to liberate Poland and Lithuania from Russian occupation. After suffering serious injury and imprisonment, he was forced to live the rest of his life in exile in a number of countries, returning briefly to America in 1797. The memorial in Philadelphia — known as “K House” to locals — is the home where Kościuszko stayed on this second visit to America, years after helping to liberate his adopted countrymen.