This permanent, outdoor installation is five large sections of the Berlin Wall, tucked near a trendy and expensive eatery in Midtown Manhattan.
Though addressed to 520 Madison Avenue, this relic of Capitalism-vs-Communism is actually located in the courtyard of the Continental Illinois Building, which is on 53rd Street, between Madison and 5th Ave.
The West face of the wall (which now faces east) holds the work of German artists Thierry Noir and Kiddy Citny, while the East face is blank.
This section of the Wall was moved here in 1990, when it was sold by the former DMP to Jerry Speyer of Tishman Speyer, the real estate developer who owns the building.
There are other pieces of the Berlin Wall in NYC, and they are located in the gardens of the United Nations headquarters, another at the marina of the World Financial Center, and a third at Ripley's Believe It or Not! Museum in Times Square, though I believe this one is the largest.