There are quite a few of these around North America. This one was built in the early 1850 on the Galt Branch Of the Great Western Railway of Canada. It is south of present-day Cambridge, Ontario. The tracks were lifted by CN in the 1980s. Luckily, there has been enough interest to keep it intact. I hope that interest remains because this culvert could last 1,000 years!
One can see the hand working with twist drills and other tooling.
There are several still extant along this right of way, but this is the classiest one.
Now, I hope the pics don't end up sideways!

Some went sideways. Not sure why or how to fix them. C'est la vie.
One stone I measured was 56x36x24 inches. All locally quarried. Hard working and skilled men.

And back in the day, under Grand Trunk care!

The sideways ones display right side up when I click on them, no problem.

Okay, thanks Sammy.
There was a bit of graffiti that someone, perhaps the Township crew, had scrubbed down a bit. Otherwise, it is all good.
CN ran a daily freight from Stratford to Lynden Junction, which is southeast of this location. That ended in the late 1970s.
I remember the 80-pound rail on this section of line. It was 1880s vintage and marked GTR. CN ran its excursion engines, 6167, 6218, and 6060 across this line many times.
The last scheduled passenger/mail trains ended in 1959. They were powered by light Pacifics. The freight was hauled by Consols at the end of steam.
My first public school was in earshot of the line. My teacher's husband worked the RPO car on the Hamilton to Owen Sound passenger train on this line unto the end of service. I am old enough to remember that service and the stations along the line. The one north of there was called Branchton, where there was a short passing siding.

The top photo, of engine #303, showing the dirt road beneath the bridge snaking off into the distance, would make a righteous painting !!! (If only I wasn't so lazy)

I'm not having much luck trying to flip other photos.

Ed,
Not sure why they go sideways, or how I can flip them after posting.

Sammy,
The tunnel itself has not changed much. It is only about five miles from me. If you come up this way, I could sit you there with your easel and paints and supply you with beverages and snacks. You could add the train and the rest at your leisure.