AT&T Madison Complex Tandem Office

The AT&T Madison Complex Tandem Office is a 17-story, 79 m (259 ft) building in Los Angeles, California, completed in 1961. With its microwave tower, used through 1993, bringing the overall height to 137 m (449 ft), it is the 47th tallest building in Los Angeles. The building serves 1.3 million phone lines in area code 213, and other Los Angeles area codes, for foreign long-distance calling. The site plays host to technology used in the NSA's Fairview surveillance program.

Building data from Wikidata (CC0); heights normalised. Summary from Wikipedia (CC BY-SA).