As the power brokers hammer out details of a master plan for the St. Louis riverfront, one item will doubtless top their to-do list: Find a way to bury I-70 in front of the Gateway Arch. Urban planners and civic boosters have long maintained that the interstate has severed the city from the Mississippi. Today's riverside-bound pedestrian must brave a gauntlet of cars and concrete -- not exactly a setup that draws folks to the waterfront. So why not cap I-70, build pedestrian-friendly retail around the Arch and reconnect the city to one of its past glories? Sure, there'll be a high-stakes wrangle with the federal government, which owns the highway and the Arch grounds. And it won't come cheap (Mayor Francis Slay will say only that "it will cost millions of dollars and take years to complete"). But in the end, the Mississippi is one of this town's greatest assets. It's high time we get to appreciate it.