As our plane landed and we made our way through customs, a tiny worry slithered around somewhere deep inside me. It began to grow ever so slowly as we made our way to the metro and boarded a train bound for Pino Suárez. As we rattled our way at breakneck speed beneath the city streets, the teensy worry grew larger yet, wrapping its cold fingers around the base of my spine.

What if we couldn't do this anymore? What if we just didn't have it in us any longer?

After all, it had been almost two and a half years since our round-the-world trip, since we'd boarded that final flight home from Thailand, by way of South Korea. And while we'd made two further excursions abroad in that time, neither of them seemed to count. Not to me, nursing my worry in silence as we trundled noisily past Zaragoza.

In late 2006, just a few months after we'd arrived home, we returned to Thailand on a mission to adopt a dog. But that was different: we were returning to Elephant Nature Park for the duration of our sojourn in the Land of Smiles, not heading off in any bold new directions. And we were just a little distracted by the whole "adopting a dog from Thailand" thing, too. So that really didn't count.

About a year later we undertook another secret mission, this time to Lima, Peru. Details of this adventure remain classified, but suffice to say we were in the company of good friends the entire time: friends who knew their way around, who hooked us up with a great hostel, who served as our "tour guides" for the trip, and who handled getting us from place to place in the megalopolic labyrinth that is Lima. It was really nice to be able to step back and go along for the ride, but it did leave us wondering if we still had it in us to do it all on our own. We'd learned so much in our travels around the world. Was it all slipping away?

There was one moment, though, where we caught a reassuring glimpse of an answer. We were heading out that night, to the home of the parents of one of our friends, and we wanted to bring some flowers. Since we had a few hours of downtime, we slipped out to make a quick run to the market.

Lima has a rather unsavory reputation among backpackers. From reading travel forums, we'd had an impression of it as an insanely dangerous conflux of crime and violence. As so often seemed to be the case in our travels, these impressions could not have been more wrong. Lima is beautiful, a patchwork quilt of stunning colonial buildings and ancient pre-colonial monuments and towering modern skyscrapers. And the 10-minute walk from our hostel to the market was like going back in time for us, back to dozens of other cities and other markets. Back to our trip. It felt like it was all rushing back to us, like it was all still there after all.

It was reassuring. But it was also a reminder that in two and a half years since our round-the-world trip, we'd only been really backpacking on our own again for that half hour at the market.

Backpacking is addictive. The more places you see, the more you realize that you haven't seen anything yet. The more countries you visit, the more places you learn about that you want to hit next. We got back from our trip firmly hooked on that Traveling Bug, and we promised ourselves that we'd keep traveling. They'd have to be smaller trips, to be sure (we didn't want to leave our doggy and kitty for another 18-month pilgrimage!), but they'd be enough to feed the Bug. We promised to leave the country (and Canada didn't count) at least once a year for the rest of our lives.

And so it was that we found ourselves in the waning weeks of 2008, realizing that we hadn't yet left the country since that trip to Peru the previous year. This was important. We had to go somewhere. But more important still, we wanted to do it right. We wanted to jump back in with both feet. We wanted to go somewhere new, and to go it alone.

But where?

We pulled open maps and pulled out our beloved Lonely Planet guides, those backpacker bibles that guided us safely around the world and back again. We toyed with dozens of places, but were somewhat limited in time and budget. If only there was something a little closer to home, so that we wouldn't squander too much precious time getting there. Maybe a place with some of that glorious architecture we admired so much in Lima, or a place with a rich culture we'd always wanted to learn more about. And since we'd only be able to travel for five or six days or so, it would be nice if it was a city we were visiting, where lots of different sights and attractions were all bundled in closely together...

Our train arrived at last at Pino Suárez, and we made our way through the crowds to the exit. After ascending the long flight of stairs, we emerged into the daylight.

Mexico City.

It was like coming up to the surface after two and a half years underwater. It was like drinking again after an eternity of thirst. All of my worries vanished, left behind in the metro station as we began making our way through the city. Just like before, it all came rushing back. The Bug was being fed.

A few minutes later we arrived at the Zòcalo, the enormous empty plaza in the center of the historic district of Mexico City. Second in size only to Moscow's Red Square, it's surrounded by all of the most important buildings in the city. To our right was the enormous presidential palace, famously decorated within by the political murals of Diego Rivera. Ahead of us stood the imposing Metropolitan Cathedral, the largest in all of Latin America. Beside it stood the Aztec Templo Meyor: the colonial and the pre-colonial rubbing elbows, as they seem to so often in this town.

I'd expected the Zòcalo to be a vast open space, as indeed it is for most of the year. But not for us, not then.

Christmas was coming, and Mexico was overflowing with the Christmas Spirit. And the entire square had been given over to it. Winter had come to the capital, as signs everywhere proudly declared. It might have been 72°F (22°C), but if we wanted we could go ice skating in a rink Rockefeller Plaza would kill to have, or sledding down a man-made hill covered in fake snow. In the center of it stood a massive Christmas tree, rising higher than the cathedral. The entire square was hung with lights, millions and millions of lights.

I loved it, and for a very simple reason. I hadn't expected it in the slightest, and that's the fun of travel for me. The things you don't expect. The quirky, oddball things about every place that you really only get to know by leaving your footprints there. It was intoxicating. I couldn't wait to see more.

But that would have to wait. We still had to find ourselves a place to stay, and we knew it might be a challenge. We'd bought out tickets before discovering that the city's most important religious event (nope, not Christmas!) would be happening while we were there. We'd be competing for lodging with pilgrims from all over the country. Obviously, we were excited because we wanted to witness it ourselves (a story for another post), but I had been a little nervous about whether every hotel and hostel in the city would be booked to capacity as a result.

Those fears, too, were gone now. As we made our way across the Zòcalo in search of a place to call home for a few days, I knew we'd be just fine.