Prior to our adventure around the world, I imagined seeing different countries, cities, villages, and major tourist sites. I daydreamed about the colors of fabrics, the sounds of instruments, and the taste of foods. And I thought about making new friends, travelers and locals alike, and gaining a new perspective about the world. But what I didn't think about – what I couldn't have known yet – was what would become the quintessential aspect of traveling for us: moments of random happiness.

Happening across people dancing together in the street, seeing shooting stars over the ocean, being invited to share tea with the caretaker of an ancient church: these moments of random happiness can't be searched for and discovered with a guidebook. Instead, they happen when and where you least expect them. Lucky for us, our recent trip to Mexico City with my sister Sheila and her husband Jeff was no exception.

It was another gorgeous morning in Mexico City. The sun was warm and there was a light breeze in the air, just enough to wave the scrumptious smells of the nearby food carts under our noses. Later in the day we'd find ourselves eating lunch on a picturesque balcony in Coyoacán, taking in the bright colors of the colonial buildings and blooming flowers. Later still, we'd do as the locals do and partake in a few games of bowling. But first we had to navigate our way from the metro to the center of Coyoacán.

To our left was a black iron fence, to our right was a busy main drag. Our goal was to find a way on to the other side of the fence, hopefully into the interior of a park we suspected to be located inside, and away from the hustle and bustle of Mexico City. Passing the vendors and turning a street corner, Tim and I had just begun to doubt our own directions when we came to one of the entrances into the Viveros de Coyoacán (Nurseries of Coyoacán).

Established in the early 1900's, the Viveros de Coyoacán are the nurseries for Mexico City's parks and gardens. Lined with jogging paths, the area is a welcome respite from the busy streets that encircle it. In fact, after walking a mere minute or so into the park, you can barely hear a car horn honk. Following the pathways deeper into the park, the four of us enjoyed looking at the well-maintained rows of young plants and flowers. It seemed like every variety of greenery was around us. But aside from the occasional jogger or a young family enjoying quality time, it felt like we were the only ones in the park (save for the rather bold black squirrels, of course).

Turning down a side path, we moved even further from the city that surrounded us. Here the only sounds were those of our shoes on the red gravel and the songs of the local birds. It wasn't until we neared the end of the path that we noticed movement and some unusual noises coming from an open area just ahead.

We could see a man with a red cape moving deftly with the grace of a dancer. And as we walked closer to the open area, we saw that he wasn't alone: there was another man standing nearby with what appeared to be bull's horns. In fact, there were several pairs of men – one man with a red cape, one man with bull's horns – scattered about the dusty space. Quickly realizing we had stumbled across matadors practicing for upcoming bullfights, we sat in hushed silence and watched the duos dance.

Sheila, Jeff, Tim, and I had spent the day exploring several sites in Mexico City including the Palacio de Bellas Artes (Palace of Fine Arts) and a market in neighboring Alameda Park. Given we had walked a considerable distance the day before, this day was meant to be a slower day. Two museums and two markets later, we realized slower wasn't quite how the day turned out. But after a few hours of siesta and some people watching from a cafe, we were ready to soak in more of the nightlife in Mexico City.

It was late in the evening when the four of us were walking around the Zócalo. Bordered on one side by the Palacio Nacional and another side by the Catedral Metropolitana, the Zócalo is a destination in its own right. And as one of the largest squares in the world, it's a hive of activity any time of day.

But it wasn't until we crossed the street to stand in front of Mexico City's Cathedral (the largest and oldest cathedral in the Americas) that we heard the singing. From deep within the cathedral we heard a gorgeous voice – something that neither Tim nor I had heard coming from the cathedral, despite the dozens and dozens of times we had walked by it before. Drawn by the beauty of the song, we said buenos noches (good evening) to the guards standing watch at the gates and passed through the massive doorway.

The interior of the cathedral was barely lit. To our left, the Altar of Forgiveness gave a golden glow, reflecting light onto a handful of parishioners silently praying in front of it. To our right, the seven chapels in the east nave were dark, save for a handful of tealight candles lit in front of them. The singing was coming from the north end of the cathedral, near the Altar of the Kings, over 100 meters away from where we were standing.

Walking along the east nave, we were momentarily between worlds having left behind the light from the Altar of Forgiveness but still moving slowly towards the light shining from the candelabras hanging in the distance. When we reached as far as we could go (tourists are asked to stand behind a low wooden fence when mass is going on), we silently stood and listened to the choir. As someone who is unfamiliar with hymns, I had no idea what was being sung. But no matter: the effect to anyone listening, I'm sure, was universal. Standing there, with one of the largest cities in the world humming and buzzing along outside, I felt completely at peace.

Settling in for the hour-long bus ride, I looked outside the window at the gathering storm clouds. We had just barely missed getting rained on by an afternoon thunderstorm, but we had front row seats for the lightening show that was set to begin among the mountains in the distance.

Having spent the day exploring the pyramids of Teotihuacan, we were taking a local bus back to Mexico City's terminal norte (north bus terminal). From there, it'd just be a short metro ride home to our hotel in Centro Histórico. Although there are overpriced tours that take tourists to the pyramids, we had opted to go on our own and couldn't have been happier with our decision. In fact, we had arrived at the pyramids well after most of the tour groups had departed. And it had been thrilling to explore the area with barely another visitor in sight, particularly when we were navigating the hundreds of steep steps to the top of each pyramid.

As some of the largest pyramids the world, Teotihuacan is definitely a must-see for a trip to Mexico City. And although it's one of the most visited archaeological sites in all of Mexico, the four of us were among the only passengers on the last bus back to the city. As the bus rolled along, I watched the world roll by outside. I couldn't help but think of the hundreds of bus rides Tim and I have taken all around the world.

Shortly after getting on to the highway, a man stood up in the aisle to address the passengers (what there were of us) in Spanish. Having adjusted to various hawkers on buses in South America, I just assumed he was selling something and looked out my window instead. And so it wasn't until the first drops of rain began splashing onto the windows that I realized the man in the aisle had started playing his guitar and singing.

There are few things I enjoy more than a bus ride in another country. Long, short, local, or long-distance, I've enjoyed nearly every bus ride we've ever taken. Sure, we've had some impossibly long rides and we've had some frightening rides, but nearly all of them have been interesting or beautiful in their own way. And while I watched the building and billboards, school kids and stray dogs that make up the outermost edges of Mexico City's massive sprawl, all set to the sounds of music coming from the aisle, I knew this bus ride would prove to be most memorable too.