The genius of cities lies in their juxtapositions. A block or two from residences, small shops bustle and thrive. On the other side of the park the train’s whistle blows. Walk a few blocks and the world, and the people, change.

There was a time in the “city planning” world when the idea was precise order and separation of uses. Industry here. Business there. Residents far away. But the most interesting cities mix it up, weaving and juxtaposing the unexpected and the dissimilar, and so stimulating a mix of people and activity, in a public life and space that is alive.

Seattle does this as well, perhaps better, than many cities.

On the recent President’s Day holiday, I did an urban bike trip, one that caused me to ponder the wonderful juxtapositions where worlds intersect and overlap here. Moreover, my route ran along  the borders between the different worlds that have so much to do with making Seattle what it is.

The ride began in southeast Seattle, near Columbia City, once the end of the line for the street car and today a case study for urban renewal of the new style. Instead of scrapping historic buildings, most have been restored and the neighborhood is alive with shops, restaurants and a healthy mix of business and residential, as well as many races and cultures.

Riding north on Rainier is easier and safer now since last summer’s Seattle Department of Transportation project to repave that arterial. The Starbucks at the corner of Martin Luther King Jr. Way and Rainier is packed, as usual, with newer immigrants, Somalis and Ethiophians among others. It may not have been what  Howard Shultz pictured when he pitched Starbucks as everyone’s “third place,” but it's definitely working.

Then my ride takes me under I-90, turning west on Dearborn to pass alongside the International District and into Pioneer Square. Pioneer Square and its cobblestones date to Seattle’s founding and before the Great Fire of 1889. There I pick up the bike trail heading north along Elliott Bay, with its mix of ferry traffic and tourist spots. The Seattle Aquarium seems to be packing families in on the holiday — perhaps to see a giant female octupus welcome her new male companion.

At my left stands the new building of the Port of Seattle, which is celebrating its 100th anniversary. Across the street and railroad tracks, the area below the Pike Place Market is thick with new apartments and condos. Then I veer into Myrtle Edwards Park, below and just west of the Sculpture Garden.

According to Celtic tradition, there are are “thin places.” It may be a well or a mountain, a particular tree or a certain valley. At the thin places the veil between this world and the next is so sheer that traffic might slip though going either direction. There’s something of a thin-place feel to this urban ride.

Perhaps it takes hold now because Myrtle Edwards really is a thin place, a narrow strip of park, bordered by the train tracks on the east and the Puget Sound on the west. You’re not quite sure if you’re in industrial Seattle or conservationist Seattle. Really, it’s both. A Burlington Northern engine creaks by on the tracks at your back as you ponder the Sculpture Park’s salmon restoration project, where children play, from a perch on a driftwood log. A comorant bobs in the waves, his head like a periscope in the up position.

While the Celts spoke of the thin places as the borderland between this world and the next, this Seattle ride places a person between Seattle’s own very different worlds. The late 19th century cobblestones of Pioneer Square, yield to the railroads of the 20th century, and then the very 21st century of Sculpture Park and public art. The cheek-by-jowlness of it all is what makes the ride so heady and fun.

Dogs and their walkers dot Myrtle Edwards. The Centennial Fishing Pier offers a perch for the urban fisherman. Coming out of Myrtle Edwards, the feel of an older industrial world heightens as you ride alongside a grain elevator, shipping docks, and more expansive rail yards. Suddenly, a father and son in full hockey gear shoot by on rollarblades, sticks in hand. Where are they going? Up a slight hill and you’re at Dravus Street and the foot of the Magnolia neighborhood.

Soon you have a choice. You can continue west into the onetime military outpost that is now Discovery Park and its headlands, or continue north crossing the Locks into Ballard. Before I head down to the Locks I notice that someone has decorated for Presidents Day. A tall thin shrub has been turned into Honest Abe with a stovepipe hat, a bearded Lincoln face mask and topcoat.

Entering the Locks, I see pleasure boats and maritime construction vessels passing through the chambers to the delight of both tourists and locals. Coming out of the Locks, another choice. A left will take you to Shilshole Marina with its forest of sailboat masts and on to Golden Gardens Park. There you can watch tightrope walkers practice on cables strung between the trees at beachside.

But today I turn right into Ballard, and for a change I’m on the main drag, Market Street, the first really main road since long ago Rainier Avenue. But it’s a short stint; at 24th I slip down into Ballard’s industrial backside, where businesses and warehouses that support the nearby fishing fleet are clustered. After passing under the Ballard Bridge, its time to pick up the Burke-Gilman Trail as it passes behind Hale’s Ale’s and into Fremont, along the ship canal. A single black scull glides along the canal, leaving swirls where the oars dip.

The mist has become rain and so Canal Coffee, which fronts onto the Burke-Gilman two blocks west of the Fremont Bridge, is a welcome stop. Inside I learn that the flag flying today is in honor of Norway's King Harald. Canal Coffee is biker friendly, with racks for locking up outside and maps inside.

Getting going again after that warm break is a challenge as it is now definitely raining and feels colder. Around the Fremont Bridge abutment and by the statue of the peace activist, Sri Chinmoy, which has been decorated with fresh flowers, spots of color against the green and grey. Soon Lake Union and Gasworks are on the right. Continuing up the trail toward the UW, beneath another bridge (I-5) where you can see the 1993 sculputure of Canadian artist, Mowry Baden, titled Wall of Death. Its location suggests the sculpture may not have been a particularly popular acquisition.    

At the University I turn south across the University Bridge and head back down Lake Washington toward Seward Park and home. Despite the rain there’s a small crowd at another shrine along the lake. It’s the pocket park next to the house where Kurt Cobain took his life.

Though I am wet and getting cold, it feels like I’ve been on a quintessential Seattle tour, my growing saturation a seeming confirmation. This urban ride takes you through a kaleidescope of worlds, university and industrial, medical and maritime, historic and residential, shipping and sculling.