The view from the top row of Mount Davis is breathtaking. You can see the skyline of San Francisco, the skyline of Oakland, the sparkling bay waters. You can monitor traffic on several freeways.

You just can’t see the baseball field. Not all of it, anyway. Most of the outfield is out of sight. Balls hit into the Oakland Triangle of outfield grass disappear mysteriously.

In the top of the fourth in Saturday night’s Giants-A’s game, Brandon Belt hit a flyball to right field. Belt trotted toward first base. Routine flyball? Those of us perched high atop Mount Davis were looking for a sign. Would Belt turn left at first base, or do a U-turn?

He turned left! Home run! Must have been a beauty. Next time, Brandon, give us a damn sign. Flip your bat.

The A’s untarped the massive concrete mountain’s upper deck for the game, with the expectation of packing it to the gills and setting a new Oakland A’s attendance record.

They did it. The announced attendance was 56,310, 472 short of capacity but still a record.

The de-tarping of the mountaintop wasn’t quite as dramatic as the opening of King Tut’s Tomb, but it did create something of a tourist attraction.

Two hours before the game, a steady stream of fans began making the hike up to the mountain, then up the steep stairways to the top row of The Most Useless Structure in the Bay Area.

Mount Davis is a little bit like the Great Wall of China, except the Great Wall has a function — keeping the Mongols out — and the Chinese people aren’t still paying off their wall.

If, as legend has it, you can see the Great Wall from the moon, you can see Mount Davis from Uranus.

It has a mystique. Fans came to summit the mighty slab, many of whom didn’t have tickets for seats up there. Why? Because it’s there. And it’s a piece of Oakland sports history, a testament to wasted money and overly dreamy dreams.

Al Davis knew how to build a monolith, but by the ’90s had lost his knack for building a ballclub.

I’ve always preferred to call the thing Al’s Alps, but that never caught on. Mount Davis was built in 1995 as part of the city and county’s desperate — and successful — attempt to lure Davis and his Raiders back to Oakland.

The A’s began tarping off the mountain’s top deck of 8,190 seats in 2006, and the Raiders in 2013.

Saturday I learned what was under the tarps. Dust. Me and the 7,000 or so fans (my estimate) who sat in the Alps were human dust rags. I sat in three or four empty seats, just because I hate to leave a job half-done.

The view from even the bottom row of the Mount is spectacular. You’re higher than the highest row of the regular stadium. You can see the top of Oracle Arena.

“Holy s—!” was a reaction I heard more than once from fans emerging from a tunnel and looking down on the diamond from blimp level. Yeah, you don’t bring a mitt to Mount Davis, unless you need a seagull shield for the late innings.

Just getting to the mountain’s base camp — the bottom row — is a trek. You either climb up and up a ramp structure, or wait up to half an hour for an elevator.

Not an ideal baseball perch. Through the first half of the game, while the infield was in shadow, the baseball was all but invisible. Watching a double play took me back to the early 1960s when major-league teams, to entertain fans before games, would perform the Phantom Infield Drill, using no ball.

It’s great that the A’s and Giants could draw such a big crowd, but it reminded me that the Coliseum folks never found an efficient way to handle traffic for sold-out games. Between the traffic jams and the long lines at the security gates, many fans got to their seats late. In the bottom of the fourth, Mount Davis was maybe half-full.

Walking around, I became a secret shopper, like one of those people hired to snoop around and assess the customer experience. In one snack-bar line I counted 60 people.

While they waited: No TV monitors, no radio broadcast. The A’s should have hired town criers. Hear ye, hear ye, the Giants just scored on a Brandon Belt circuit clout to take a one-to-nothing advantage!

Helping kill the tedium, a man and woman wearing Giants garb got into some kind of beef and wound up cuffed and arrested, the woman struggling on the concrete floor for several minutes.

But Bay Area fans are tough. The Mount Davis expeditioners seemed to enjoy the game and the great weather. They made history, and I hope they all escaped the mountain before it was re-tarped.

Scott Ostler is a San Francisco Chronicle columnist. Email: sostler@sfchronicle.com Twitter: @scottostler