While I was loitering in the main atrium of the National Gallery of Art, I overheard a woman talking on her phone, trying to meet up with someone.

“You’re in the wrong building. This is the big one, not the pointy one,” she said.

I imagine this is a conversation that happens often, because the NGA is enormous. The lost friend was in the museum’s East Building, a 450,000-square-foot structure that holds the NGA’s modern art collection. The West Building, where I stood, is even bigger, a 547,000-square-foot neoclassical temple holding nearly 3,000 masterpieces representing about 600 years of Western art.

Since I had no idea where to start, I joined a free tour called “Great Paintings: The Nation’s Collection.” Also along for the tour: a woman and her two daughters visiting from a nearby suburb, three sharply dressed young men and a 50ish woman.

Our guide, a woman with a head of tight gray curls, led us into a gallery of Renaissance paintings.

“We are going to look at a painting of Leonardo da Vinci’s,” she said. “It’s the only [painting of his] that’s in any public facility in all of the Americas, so it’s pretty special.”

We gathered around a portrait of a somber-looking 16-year-old named Ginevra de’ Benci. The guide asked us what adjectives we would use to describe the teen, and one of the young men piped up.

“She looks disappointed in me, like I made a bad fashion decision and I really should have known better,” he said.

“Hmmm, that’s interesting,” our guide said, her voice lilting upward in a clear indication she thought his answer was dumb.

The response she was looking for was eventually provided by the 50ish lady, who turned out to be a stealth art historian. “She’s beautiful, almost glowing,” the woman said, adding, “Da Vinci created the girl’s luminous complexion by applying many thin layers of oil paint.”

Not to be outdone by the tourist, our guide added that the painting might have been commissioned by one of the girl’s many “platonic lovers” — a common practice among the Italian aristocracy at that time.

“What is a platonic lover?” the mom asked.

“Theoretically, it means there’s no sex,” our guide said, looking embarrassed.

“That’s weird,” one of the young men commented. “I don’t believe it.”

“Let’s move on,” the guide said, putting an end to the debate. “Now we are going to go to Rome…”

As we reconvened in the hallway, it became clear that most of our group had quit the tour, quietly hanging back or disappearing into other rooms. It was down to just me and the 50ish lady.

“Are you still interested?” our guide said, sounding a little needy.

“Yes, definitely!” I said with excessive enthusiasm so she wouldn’t feel rejected.

We gathered around a piece painted by Raphael known as “The Alba Madonna.” It shows a sad-looking Madonna holding a baby Jesus, who is being handed a cross by a baby John the Baptist. Both babies seemed bizarrely muscular, like they’d been lifting weights at a special gym for toddlers. (“You can do it,” I can hear baby Jesus telling his cousin. “Just two more reps before naptime!”)

“Why do you think the Virgin Mary looks sad?” the guide asked. For once, I knew the answer, because it’s always the answer for this kind of painting.

“Because she knows that Jesus is going to get crucified,” I said.

“Yes, you got it!” she said. I beamed. Even though I graduated from college nearly 20 years ago, apparently I’m still trying for that A+.

Still, I was feeling a bit down, perhaps because I’d just spent 30 minutes looking at rather depressing paintings. Somber faces, subdued colors — the liveliest painting we saw on the tour turned out, upon closer examination, to be a saint right before he’s flayed alive. The penultimate painting on our tour, a self-portrait of Rembrandt, was perhaps the most melancholy of all.

“Some really sad things did happen to him,” the guide said of the Dutch master. “His wife died, and he wasn’t able to marry his mistress because he wouldn’t get the inheritance.”

“Poor guy,” my fellow tourist said sassily.

We continued on to the Impressionists gallery, which was positively bustling compared to the sparsely populated Renaissance and Baroque rooms. I pointed this out to our guide, who said it’s because people are simply more familiar with Monet and his compatriots. I, however, suspect it’s because these 19th-century paintings are more colorful and lively — some of the people depicted are even smiling!

We stopped at a painting by Edgar Degas called “Four Dancers.”

“How many dancers do you see in this painting?” our guide asked.

Sensing a trick question, I looked more closely and saw that the dancers were all fixing the same strap on their shoulders. It had never occurred to me before, but unless there was a costume malfunction that simultaneously befell the entire corps de ballet, this picture is of one dancer in a quick succession of positions, like four snapshots combined into one photo.

“Well, that’s really cool,” I said.

“Aren’t you glad you stayed for the whole tour?” the guide asked. And I really, honestly was.

More adventures with the Staycationer