New York's Chinatown is not generally thought of as a center of high culture — it is where many of us go to get regular doses of better Chinese food than we can make ourselves, and for some kind of validation of our Chinese identities. But here and there you can find the real zìjī 字跡 of famous calligraphers. Here are four, which I've supplemented with links to Robert K. Chin's superb website:
Yú Yòurèn 于右任, scholar and politician, on the Chinese American Veterans Memorial Arch at Kim Lau Square (off Chatham Square). "華裔軍人忠烈坊" [square for soldiers of Chinese descent who died for their country]. (http://www.nychinatown.org/storefronts/chatham/chathamsqarch.html)
Cheng Man-ch'ing [Zhèng Mànqīng] 鄭曼青, artist and tàijíquán teacher. on the second-floor sign of the New York T'ai Chi Association, 209 Canal St. "太極拳學社" [Tàijíquán Study Society]. (http://www.nychinatown.org/storefronts/canal/209211canal.html)
Hu Shih [Hú Shì] 胡適, intellectual historian, on the doorway of the First Chinese Baptist Church 中華第一浸信教會, 21 Pell Street (south side of the street). "紀念堂" [memorial hall]. (http://www.nychinatown.org/storefronts/pell/21pell.html)
Chairman Mao [Máo Zhǔxí] 毛主席, on the sign of the Xīnhuá Bookstore 新华书店, 9 Elizabeth St. (west side of street). "新华书店" [Xīnhuá Bookstore]. No image yet, and the same calligraphy is used on all the store's signs around the world, so this is rather less distinctive.
I'd be glad to hear of any others, and I'll list them here. Or if you have more detailed photographs, those would be nice, too.