In the 30's Paseo del Rio was known among San Antonians as a brief, dark experience normally ending in death, and in the 40's it was off-limits to military personnel. Tourists would go down one stairway and never come back up the other one. The whole notion of a pedestrian walkway along the San Antonio River, one story under street level, had been the brainchild of an architect named Robert H.H. Hugman. It was partly a flood control measure. His developers were careful to plan around existing live oak trees, and, to prove a point, Hugman even installed his office down there, next to the Riverwalk's first restaurant, Casa Rio. He was widely expected to drown like a rat in the next flood.

"Crucial funding came in 1939 under the WPA and resulted in the initial construction of a network of some 17,000 linear feet of walkways, about 20 bridges, and extensive plantings including the live oaks whose branches are visible from street level."

Since then the Riverwalk has grown steadily more popular, upgraded and improved and extended to many times its original size, and now it dominates the city from underneath. The river itself is more like a canal, three or four feet deep, greenish, still, and dredged in an entertaining annual ritual. They find all KINDS of things in there. It winds and loops under bridges and between two parallel sidewalks lined with restaurants and shops, connecting the major tourist draws from Alamo Plaza to Rivercenter, to Hemisphere Plaza, to the Transit Tower (which stays lit from dark to midnight or so and crowns the city like a big beautiful Gothic wedding cake).

When I worked for that Cuban figure (the one who made all his money exporting breakfast cereal during the sugar embargo) in San Antonio I used to walk around every day at lunch. From the Alamo grounds, the Riverwalk, the Menger and the Gunter, the Cathedral, the King William district, the lonely old Herzberg, the city's inexhaustibly rich.

Most downtown buildings have street entrances and separate river entrances below, and the city has an intricate, almost-Venetian network of bridges, walkways and old staircases, and the leaves of the huge old trees growing below are visible from the streets above. This manmade canyon winding through the street grid makes San Antonio humane and friendly. As a tourist attraction it's finally an unqualified success. As an architectural feature it provides visual and haptic complexity and an urban energy that's hard to describe, but easy to sense. There's an almost European density.

From an urban planning standpoint, the Riverwalk is a wonderful example of a pedestrian-only realm, no motor vehicles or bicycles allowed. It's a big system which achieves a nice balance among retail, commercial, greenspace and cultural uses. Admittedly, though, nobody much lives downtown, and right outside of downtown San Antonio is as car-oriented as any other Sun Belt city and, especially along the northern section of the Connally Loop, shockingly, nakedly corporate-suburban-automotive.

Take a boat tour if you can -- preferably at night when they light up the trees. Preferably around Christmas. The branches of the live oaks extend horizontally almost clear over the quiet river. With cool breezes on the river, a completely likable Mexican guide who tells stories about the places you pass, and the food smells and music wafting from the restaurants as you go by, you get the full relaxed, romantic, magical, semi-tropical feel to the place -- like a foreign capital.

And although it's been increasingly slicker through the 90's, with the Planet Hollywood virus etc., the Riverwalk has never had a corporate sponsor and it grows out of a community feeling that's natural, mature, and genuine.