Ashburton House - Credit: Wikimedia Commons
Ashburton House, also known as St. John's Church Parish House or the British Legation, is a historic house at 1525 H Street NW, on Lafayette Square in Washington, D.C. Built in 1836, it is notable as the residence of Lord Ashburton in 1842, during which time negotiations took place there culminating the Webster–Ashburton Treaty. This settled a long list of border disputes between the U.S. and the British provinces that are now Canada, and ended the Aroostook War. It was declared a National Historic Landmark in 1973. and  It presently serves as the parish house for St. John's Episcopal Church. Read more on Wikipedia
Source: en.wikipedia.org