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

Inside, there's a replaceable CR2016 watch battery that's said to last more than a year, a Bluetooth module and antenna, an LED-lit ring and a piezoelectric speaker.

ENGADGET: StickNFind Bluetooth stickers let you tag and locate your goods with a smartphone (hands-on video)