I just got back from the most fascinating day trip I’ve taken in years, and not only was it free – I didn’t even have to leave town.

Walking above and below ground for miles through downtown Houston, where I had a business engagement, I experienced the same sense of wonder that I felt the first time I embarked on this urban adventure many years ago. I saw an old friend with newly appreciative eyes.

Downtown Houston is the only place where you can fully grasp the fact that Houston is, indeed, a big city — in fact, the fourth-largest in the United States. Here, during business hours, populated by an estimated 140,000 workers Monday through Friday, you can really feel the invigorating energy that’s always distinguished the dynamic spirit of Houston. You’re surrounded by office workers, wearing downtown dress-code apparel, all walking that trademark big-city-brisk walk through the streets if the temperature is accommodating, and if not, through the most gratifyingly efficient transportation system in town: The downtown tunnel.

If you don't work downtown, I bet you’re a lot like me. You drive downtown on spot visits directed toward one specific site and purpose: A business engagement, a concert, a show, or a restaurant meal with friends. During the nine months of the year that comprise the performing arts season, I consider myself an integral part of the nocturnal landscape of the Theater District. I know the district like the back of my hand. But that’s only a small part of the big picture of downtown Houston.

Recently, I luxuriated in a comfortable stroll, sightseeing in my Sauconys (versus the dress heels I wear for short walks to evening events in the Theater District). Everything looked so new, huge, and impressive. It had been so long since I’d last walked through and really looked at my own city’s central business district, I simply didn’t remember how magnificently high all those architectural showcase buildings loomed. For years, I had been looking at downtown Houston’s beautiful skyline in glimpses from my car, from a distance. I could see the forest, but not the trees.

Just as with any work of art, you can’t get the whole picture if you only look at it from a distance. You have to get closer, and look at it from various perspectives over time, savoring the revelations that suddenly leap out at you with each new view.

Still standing among all the modern skyscrapers were a number of the stately old downtown landmarks I have loved for so long, like the Niels Esperson Building, originally developed in 1927. I was also glad to see that, despite the increasing heat at mid-day, many other people were out walking on the streets, enjoying the view along their way.

After my appointment, on my way out of the building, the weather had become unpleasantly hot, so I decided to take the tunnel as far as I could on my way back to my garage. I was delighted to find that the tunnel had expanded tremendously —both across and down, like a big crossword puzzle — since I last used it on a daily basis when I worked downtown many years ago.

These days, you can walk underground throughout the entire downtown area via the comfortably air-conditioned, 6.3-mile-long tunnel system, which is equipped with cafes, shops, maps and overhead markers, and courteous downtowners who don’t mind pausing to offer additional directions.

Suddenly, all these dots connected. Walking through the heart of this high-energy city made me see Houston with fresh eyes. I was able to see, close up, why a neighbor recently told me she was thinking of moving from our sedate residential neighborhood outside the Loop to a loft downtown – one with sky-high ceilings and huge windows offering spectacular views from atop a renovated old treasure of a building, I enviously imagine.

Taking a different path on my visit downtown unexpectedly expanded my perspective, opening up all kinds of interesting new views, ideas, and possibilities. How long has it been since you’ve taken a walk through downtown Houston and seen all the opportunities lying right at your feet?