Many people felt this was unfair, because the Sears Tower's tall antenna was not included in the official height measurement.

VOA: special.2010.03.31

This makes them easy to set up--no tower or central antenna needed--as well as hard to knock out, since if one device goes down, the others will route around it.

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On this day, the One World Trade Center workers were lowering in to place the very first ring that would support the spire, or antenna, of the tower.

FORBES: A Tour Of One World Trade Center

It leases and manages antenna space on its multi-tenant communications tower sites to wireless service providers and radio and TV broadcast companies.

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