Mood: special
Daryl recently posted the question of whether or not the WTC towers can be seen in the 1969 movie Midnight Cowboy. I took some time to research this quesiton and here is what I've concluded.
I believe I found the shot you mentioned at the 13 minute mark in the movie. You thought the building far to the left was one of the towers under construction. (I drew an arrow to the building I assume you meant.)
I then took a look at other buildings around it to decide what part of Manhattan we are looking at. It's easy to identify the Empire State Building. Farther to the left is the Chrysler Building and the building tht looks somewhat like the World Trade Center is actually the MetLife Building. (Look it up in Wikipedia/Google Maps for better photos and distance between the buildings.)
These three famous landmarks are located about 4 miles north of where the World Trade Center was indeed under construction in 1969 when the movie came out. The separations in the MetLife building are similar to the WTC, but at that time, there would have been cranes visible on top of the WTC towers.