The 120-foot-wide canyon was defined by oxcarts in the 18th century and mapped in 1847, but that's hardly the end of the story. So without further ado, observations from a recent stroll. Or as Charles Keeler wrote in 1902's "San Francisco and Thereabout," "Nearly everyone seems to bound up Market Street, either a-foot or a-cable, so why not follow the crowd?"

Some things don't change. The first thing I see upon emerging from BART at Spear Street is a flower vendor, selling bouquets from a stall made to resemble (oh so vaguely) a cable car. The scene would be appreciated by authors of the 1940 Work Projects Administration guide to San Francisco.

"The curbside stands were first licensed in 1904," the guide explains. "All attempts to suppress them have been halted by storms of protest from press and public."

Plenty else does. The same book defines Market's busiest stretch - "along whose broad sidewalks moves the informal pageant of San Franciscans on parade" - beginning at Montgomery Street, five blocks to the west. No longer. The action pushes all the way to the bay, though 1983's lifeless Federal Reserve Bank with its pompous colonnade sits on this block as a reminder that not all change is good.

A little color goes a long way. The redesigned plaza two blocks west at Fremont Street is as expensively austere as they come, a black granite plateau that urges you to keep moving. But slow down anyway to enjoy the procession of red geraniums in the raised planter along the sidewalk. They're a welcome splash in the masonry gloom.

Skateboarders are not welcome. The planter's ledge offers comfortable seating, by the way, with its two-inch-thick slabs. Take note: there's an inch-wide gap between each slab - an interval intended to make it more difficult to run renegade wheels along the edge.

Art can hold its own. Tucked into a deep thin plaza at 425 Market through Aug. 29 is a quartet of life-size horses by Deborah Butterfield. They're cast bronze, though each looks like a driftwood collage, and the skeleton-like forms are a mesmerizing counterpart to the close-pressing towers and the workers laughing amid cigarette smoke. The weary gray-black tone of the bronze is fitting as well: It's hard to imagine this inlet of a plaza ever getting much sun.

Big moves are hard to fix. Market Street's wide sidewalks aspire to greatness with their red-brick paving, granite curbs and double rows of Sycamore trees. The design is vintage 1960s, rolling out the urban carpet, and no doubt it looked good on paper. But it never became the grand boulevard the boosters promised.

Now there's talk of redoing Market to emphasize mass transit and pedestrians over automobile convenience. Not a bad idea. Unfortunately, this highly defined high-quality vision from the past will make future refinements difficult - and expensive.

The recession is on display. And not just in the procession of empty storefronts, such as the Virgin Megastore at Stockton Street. Across the way is a nothing-special flatiron building from 1908 where the ground floor is being remodeled for the Diesel clothing store. The nine floors above the ground were to be spiffed up as well. Instead, there's a deadly coat of black primer on display, waiting to be covered in gray paint. Ho-hum.

This is a dividing line. Market Street is the perfect scale for marches - those rainbow flags flapping on lampposts are a reminder that the Gay Pride Parade takes place on June 28 - and on a map it looks like a centerpiece. In reality, it serves as a boundary, the line where neighborhoods start and stop.

Advocates and planners and politicians need to keep this in mind as the debate continues over the street's future. Take away cars and you'll still have the daunting width, the view-blocking buses and streetcars, the clutter of news racks and transit islands.

Market Street downtown is many things, for better or worse. But it isn't cozy. It was never meant to be. And that's fine.

Place appears on Tuesdays. E-mail John King at jking@sfchronicle.com.

This article appeared on page E - 1 of the San Francisco Chronicle