Staten Island Tunnel
... that at 10,400 feet (3,200 m), the Staten Island Tunnel would have been the world's longest tunnel, but it was abandoned after only 150 feet (46 m) of it had been built?
... that at <span about="#mwt26" data-mw='{"parts":[{"template":{"target":{"wt":"convert","href":"./Template:Convert"},"params":{"1":{"wt":"10,400"},"2":{"wt":"ft"},"3":{"wt":"m"}},"i":0}}]}' id="mw4w" typeof="mw:Transclusion">10,400 feet (3,200</span><span about="#mwt26" typeof="mw:Entity"> </span><span about="#mwt26">m)</span>, the <b id="mw5A"><a href="./Staten_Island_Tunnel" id="mw5Q" rel="mw:WikiLink" title="Staten Island Tunnel">Staten Island Tunnel</a></b> would have been the world's longest tunnel, but it was abandoned after only <span about="#mwt27" data-mw='{"parts":[{"template":{"target":{"wt":"convert","href":"./Template:Convert"},"params":{"1":{"wt":"150"},"2":{"wt":"ft"},"3":{"wt":"m"}},"i":0}}]}' id="mw5g" typeof="mw:Transclusion">150 feet (46</span><span about="#mwt27" typeof="mw:Entity"> </span><span about="#mwt27">m)</span> of it had been built?