A message we saw in Louisville recently.

Not something you see that much, not put quite that way. Maybe that’s an unconscious acknowledgment that nowhere in Scripture is Jesus’ exact birthday ever mentioned. It reminded me of a scene from Full Metal Jacket.

The message was in lights, and there was a good reason for that. It was part of Lights Under Louisville, an annual display of Christmas lights by Mega Cavern. A lot of lights: at 7 million, said to be the largest such light display in the world.

Mega Cavern is an attraction south of downtown Louisville, and a fairly recent one at that, opening for tourists only in 2009. In the mid-20th century, miners extracted limestone from under the area’s hills, eventually creating 4 million square feet of space. In comparison, the Sears Tower totals 4.4 million square feet, so nearly a Sears Tower worth of space was excavated under a section of I-264 and the Louisville Zoo and a major city park. By the early ’90s, mining had ceased, and the voids were developed into warehouse space.

In that, the place naturally reminded me of SubTropolis in Kansas City, Mo., which I visited in ’99. Unlike that man-made cave, which is still all business, Mega Cavern started adding activities for visitors, at first tours through the cave. There is still underground warehouse space, and tenants for it.

But now the facility also has underground zip lines, an aerial ropes course, and walking and tram tours most of the year. Mega Cavern used to have an enormous dirt bike course, at 320,000 square feet said to the the world’s largest underground off-road bike facility, but that didn’t last (I suspect insurance issues).

Around Christmas, you can either drive through Mega Cavern to see the millions of lights, or pay a little more and ride on a wagon pulled by a Jeep, which is what we did on December 30. It was the only activity on this trip that I had to book in advance.

The public entrance to the cave doesn’t even hint at what’s below.

At the end of a short hall is a large room used to turn vehicles around, and as a waiting area for those riding trams.

Beyond that is a room with the service desk, a small snack shop, a gift shop and a view of some climbing equipment.

We’d come for the Christmas Express.

Of we went, exactly as scheduled. I was expecting the lights to be arrayed in tree-oriented abstractions. Or just to be artful strings of lights.

There was a lot of that. At the risk of sounding churlish, since we enjoyed riding through the lights thoroughly, the ride could have used more displays like these. Most of the displays had themes. Such as local themes. They were artful, too, just not quite as spectacular.

Patriotic themes. Many more than this.

Christian themes.

Movie franchises. More than pictured here, but I don’t remember all of them now. Many geared to children. I’d heard of almost all of them.

I remember a few omissions. Star Wars – more than one display, I think. But no Star Trek. Also, Barbie. Were pink Christmas trees in vogue over the holidays? Experts say yes. But what, no Oppenheimer? C’mon, they were peas in the same summer blockbuster pod.

I’m pretty sure a Manhattan Project display would have harshed everyone’s holiday buzz, so no go. But can you imagine? The centerpiece of the Oppenheimer display would, of course, be a mushroom cloud in holiday lights.