This is part of the Historical Bridges of Hunterdon County (and sommerset)
There is a town nearby named Three Bridges, named after the three bridges you needed to cross to get there. These are not those three as they were wooden. (side note "someone" tried to burn the town of 3 Bridges down in 1875!)
Even after some research at the Three Bridges Library, I'm still not sure where they- All originally were wood and or covered bridges and long replaced. So let's move on to Neshanic Station's 3 bridges.
The beautiful white bridge here is a quite historically important, rare lenticular bridge (think "lens") with views of an old mill.
At posted coords, try to read the sign.
If the builder's company was in New Jersey, find the cache at: N 40° 30.552′ W 74° 43.650′
If the builder's company was in Connecticut, find the cache at: N 40° 30.585′ W 74° 43.592′
If the builder's company was in New York, find the cache at: N 40° 30.571′ W 74° 43.594′
If you have trouble reading the sign, find the cache at: N 40° 30.585′ W 74° 43.592′