San Telmo is the oldest neighborhood in Buenos Aires. It is also the smallest of the city’s 48 barrios measuring a mere .75 square miles. Among its charming features are cobblestone streets and colonial buildings. A worthwhile attraction is the National Historical Museum. The setting is in this early 19th century mansion once owned by Charles Ridgley Horne. The exhibits trace Argentina’s freedom from Spain. The focal years are 1810 through 1818, beginning with the May Revolution and ending with the Argentine War of Independence. Other displays highlight colonial times and the indigenous people who lived along Río de la Plata prior to the arrival of the Spanish.