We had been waiting 30 minutes for the tour to begin. Stepping into a small spot of shade, I wiped the sweat from my face. It was only 10:30, and already the temperature had soared to 95.

"I thought this tour was supposed to start at 10," I grumbled to my husband, who was also angling for shade.

"It was also supposed to be a private tour," he said. "But there are 19 of us."

My husband and I like private tours when we travel, to avoid the sort of scenario we were currently experiencing. Group tour guides are informative and engaging, but there are always tourists who can't keep up, want to cut the excursion short, or show up late.

Today, two people hadn't shown up. The excursion was supposed to be a nine-hour walking tour of Rome, and I was ready to get started. Our guide, an Italian woman with thick, black hair and a round face flushed with heat, tried to keep the 19 tourists in our group cheerful.

"Just a few more minutes. I believe the late ones are coming," she chirped, forcing a smile. "Ah! Here they are!"

I watched as two grumpy blonde women trudged through the crowd towards our group. One was youngish, her expression sullen, and the other was older, lines of dissatisfaction etched in her face. I immediately assumed, correctly, that they were mother and daughter. They did not apologize for being late.

After our guide, Camilla, herded us together, she held up a flagpole with a green scarf swirling around it. "Keep the green scarf in sight and you won't get lost," she said as we followed her down the street to join throngs of people pouring into the Vatican.

I had been to the Vatican years before and was eager to see the Sistine Chapel and St. Peter's Basilica again. Our tour had been billed as "stress free with skip-the-line tickets and transportation included, so you can enjoy your guide's fascinating narrative of the iconic sites of Rome."

After waiting 45 minutes to begin the tour, I wanted to make up for lost time, but as soon as we entered the bag check area on the lower side of the facade of the basilica, the two women who had made us late demanded a restroom break. This meant our group had to wait another 20 minutes.

I don't begrudge anyone a bathroom break, but the rest of our group was out of the restrooms in 5 minutes.

"All right! I have your tickets! Let's stay together," Camilla called cheerfully when mother and daughter finally reappeared. "Remember to follow the green scarf."

We stepped through the ticket turnstiles onto a long escalator, and when we drew close to the top I glanced back, spotting the two blonde women far below, behind another large tour group.

I wondered briefly how they had gotten so far behind, but after that, I lost sight of them. We reached Saint Peter's Square, the large plaza in front of the basilica, and our guide was describing the history of Vatican City when she realized the women weren't with us.

"Have any of you seen the mother and daughter?" She whipped a phone from her purse and called someone in her office to explain that she had lost two tourists. Then, worry creasing her face, she told the rest of us to wait while she searched for them.

"This is ridiculous," said a tall Italian man traveling with his teenaged son. "We are losing time on our tour because of those two."

Ten minutes ticked by before Camilla returned without the women. I noticed as she hurried across the plaza in her loose, flowing green dress that she was pregnant; something I had overlooked before. Perspiration plastered dark strands of hair to her face.

"I couldn't find them…" she began when the Italian man spotted the women. "There they are!" He shouted, pointing in their direction.

Camilla rushed to greet them, and the older one jabbed a finger in her face. "You are the worst guide! You hurried along so fast, leaving us behind!"

The other tourists rolled their eyes, but I was furious. This had gone far enough. Stepping toward the trio, I said, "I'm going to let those inconsiderate women have it. They've cost us an entire morning!"

My husband laid a restraining hand on my shoulder. "Don't butt in. Let the guide handle it."

"But they held the entire group up! Our poor guide tried her best and they're shaking a finger in her face!"

"She can handle it," he said. "You'll only make things worse."

He was probably right. I imagined the headlines: "American woman gets into brawl with other tourists during Rome walking tour."

No one else in our group was coming to the tour guide's defense, so I reluctantly held back. Camilla apologized several times to the women, who kept repeating, "We are going to report you to your management."

She managed to quiet them down enough to lead us inside for our tour of the Vatican Museum and the Sistine Chapel, but because we were running behind schedule, we were forced to dash through, pushed along by other tour groups and guards.

Visitors are supposed to remain silent in the Sistine Chapel, due to its sacredness. With such a large number of people crammed together, the noise of everyone talking could destroy a spirit of reverence. But in the silence of the Chapel, the women continued to berate our guide in loud whispers.

After we left the Vatican, Camilla led us through the usual Rome tourist highlights, explaining the history of Palatine Hill, the Roman Forum, the Pantheon, and Trevi Fountain.

Despite the heat and crowds, I reveled in hearing Rome's ancient history and viewing these ruins juxtaposed against a vibrant, modern city.

After lunch, I spotted our tour guide standing alone and took advantage of the moment to tell her how sorry I was she had endured such a hateful diatribe from two inconsiderate tourists.

Tears sprang to her eyes. "Thank you for your kind words. Maybe those women are stressed by the heat, the travel, or something else in their lives. I just want everyone to have a good time."

I discovered from our conversation that she had her own stresses to deal with. The night before, her husband had been rushed to the hospital, and she was forced to make last-minute arrangements for her two children so she could report to work.

I admired her patience and perseverance. I would be fired in an instant if I were a tour guide dealing with these tourists, but she took everything in stride, retaining her good cheer as she maneuvered our group through throngs of tourists and unrelenting heat.

One of the highlights of our tour, which helped me forget my anger, was the ancient Roman site where Julius Caesar was killed. We descended 20 feet below the modern city and walked on a wheelchair accessible boardwalk around the Largo di Torre Argentina, which includes four temples dating from the 3rd century BCE.

Camilla told us this area had only recently opened to the public and was not yet a popular tour group destination. Only a few people meandered around these ruins, which made it a nice respite from the crowds.

I was interested to discover that the luxury jeweler Bulgari had financed restoration of this ancient landmark, just as the luxury fashion house Fendi paid to restore the crumbling Trevi fountain. In the case of the Trevi fountain, there was one downside to the deal. It closed several days for a Fendi fashion show. But I guess a fashion show is a small price to pay for having one of Rome's iconic places restored.

Our last destination was the Colisseum, which I had visited on an earlier trip to Rome. But thanks to Camilla's extensive knowledge, I learned a lot more about its history.

The 2,000-year-old amphitheater seated 80,000 people, and in its heyday, everyone was allowed to come once a week for free wine, food, and entertainment. A bloodthirsty audience poured into the Colosseum at lunch time to watch gladiators and crucifixions. Women and children sat at the top with slaves, for safety reasons since there were wild animals and so much bloodshed in the arena.

A technological wonder, the Colosseum had a retractable roof. "We know this because the coins of the era show the Colosseum as it looked then," Camilla explained. "The arena floor was a wooden platform covered with sand that was good for soaking up blood."

The arena could also be flooded for boat shows, meant to reveal the superiority of Roman sea power.

As Camilla explained the fascinating history of the Colosseum, the two blonde women approached to say they were leaving the tour early.

"We're tired and my mother isn't feeling well," the younger one explained. Then they surprised me by hugging Camilla and thanking her for everything.

Once again, I admired her amazing patience. The tour had been a good one, despite its rocky beginning, and our knowledgeable, cheerful guide was largely responsible. Although I prefer a private excursion because of tourists like the ones we encountered, an excellent guide can make any tour a memorable event.

Bebe is a writer, editor, publisher, traveler, spouse, parent, and grandmother. She was prompted to write this article about a near-confrontation with another tourist in Rome after reading a story by Roz Warren, Writing Coach.