A tunnel of course. this one is in Zion (of course are you sick of these pictures or what? to bad)
a crazy windy road gets you up to this point. And of course the road had to be under construction since it is summer and that is the only time they can do road construction there. Sorry shot from the car window .
The above picture was taken going about 30 mph through the tunnel. crazy thing I had never seen before. they had several of these opening in the tunnel where you could see out. the best we figure is it was for natural lighting to save on not putting lights in there.
here is a shot of one of those wholes in the tunnel. at first we thought it was for water drainage which it very well still could be. you see in sandstone its like a sponge it soaks up the water and then it travels through it till it can find an out. that out is when it hits no porous rock like granite and then it drips through. probably saves from having a mess inside the tunnels too.