Of all the rooms and halls and landmarks that make up the White House and its grounds, it was the West Colonnade that I loved best.

For eight years that walkway would frame my day, a minute-long, open-air commute from home to office and back again. It was where each morning I felt the first slap of winter wind or pulse of summer heat; the place where I’d gather my thoughts, ticking through the meetings that lay ahead, preparing arguments for skeptical members of Congress or anxious constituents, girding myself for this decision or that slow-rolling crisis.

In the earliest days of the White House, the executive offices and the First Family’s residence fit under one roof, and the West Colonnade was little more than a path to the horse stables. But when Teddy Roosevelt came into office, he determined that a single building couldn’t accommodate a modern staff, six boisterous children, and his sanity. He ordered construction of what would become the West Wing and Oval Office, and over decades and successive presidencies, the colonnade’s current configuration emerged: a bracket to the Rose Garden north and west — the thick wall on the north side, mute and unadorned save for high half-moon windows; the stately white columns on the west side, like an honor guard assuring safe passage.

As a general rule, I’m a slow walker — a Hawaiian walk, Michelle likes to say, sometimes with a hint of impatience. I walked differently, though, on the colonnade, conscious of the history that had been made there and those who had preceded me. My stride got longer, my steps a bit brisker, my footfall on stone echoed by the Secret Service detail trailing me a few yards back. When I reached the ramp at the end of the colonnade (a legacy of FDR and his wheelchair — I picture him smiling, chin out, cigarette holder clenched tight in his teeth as he strains to roll up the incline), I’d wave at the uniformed guard just inside the glass-paned door. Sometimes the guard would be holding back a surprised flock of visitors. If I had time, I would shake their hands and ask where they were from. Usually, though, I just turned left, following the outer wall of the Cabinet Room and slipping into the side door by the Oval Office, where I greeted my personal staff, grabbed my schedule and a cup of hot tea, and started the business of the day.

Several times a week, I would step out onto the colonnade to find the groundskeepers, all employees of the National Park Service, working in the Rose Garden. They were older men, mostly, dressed in green khaki uniforms, sometimes matched with a floppy hat to block the sun, or a bulky coat against the cold. If I wasn’t running late, I might stop to compliment them on the fresh plantings or ask about the damage done by the previous night’s storm, and they’d explain their work with quiet pride. They were men of few words; even with one another they made their points with a gesture or a nod, each of them focused on his individual task but all of them moving with synchronized grace. One of the oldest was Ed Thomas, a tall, wiry Black man with sunken cheeks who had worked at the White House for forty years. The first time I met him, he reached into his back pocket for a cloth to wipe off the dirt be-fore shaking my hand. His hand, thick with veins and knots like the roots of a tree, engulfed mine. I asked how much longer he intended to stay at the White House before taking his retirement.

“I don’t know, Mr. President,” he said. “I like to work. Getting a little hard on the joints. But I reckon I might stay long as you’re here. Make sure the garden looks good.”

Such images would often flash through my mind, interrupting whatever calculations were occupying me. They reminded me of time passing, sometimes filling me with longing — a desire to turn back the clock and begin again. This wasn’t possible on my morning walk, for time’s arrow moved only forward then; the day’s work beckoned; I needed to focus on only those things to come.

The night was different. On the evening walk back to the residence, my briefcase stuffed with papers, I would try to slow myself down, sometimes even stop. I’d breathe air laced with the scent of soil and grass and pollen, and listen to the wind or the patter of rain. I sometimes stared at the light against the columns, and the regal mass of the White House, its flag aloft on the roof, lit bright, or I’d look toward the Washington Monument piercing the black sky in the distance, occasionally catching sight of the moon and stars above it, or the twinkling of a passing jet.

In moments like these, I would wonder at the strange path — and the idea —that had brought me to this place.

Listen to a clip from the A Promised Land audiobook, read by Barack Obama