This mile has two possible endings -- kind of like one of those interactive mystery stories. And you've got to hoof it. But it has only one beginning, the mansion built by G. Sherman Chides in 1925 at 1 Fifth Ave., the southernmost end of Bryant Park. You can't miss it -- "La Florentia, The Wedding Cake Castle," a fantastical confection decked out in turrets and chimneys, festooned with pineapples, and gates guarded by two stone lions (and, judging from the signs, at least that many German shepherds). Stand there gaping. Then take the path by the Intracoastal, feeling glad that the unbroken line of condos across the water is -- well -- across the water. Pass the Guatemalan boys playing soccer on the green and the teenagers groping each other on picnic benches. Tempting as it is, just walk on by the multilevel wooden playpark -- you're too heavy for that rope swing and too fat to fit through the tube slide. Pass the listing old cypress trees carved with lovers' names ("Alex and Amber," "J.D. loves Amanda"), the boat ramp ("Be a Better Boater! Watch out for Manatees!"), the fogies parked in their lawn chairs, the shuffleboard courts. Here's your crucial decision. Straight on takes you to the remnant of the old Lake Worth bridge, stinky with bait blood and spilled wine, populated by the most diehard group of fishermen you're ever gonna meet (no one has hooked so much as a boot there since 1975). Or if you're coming with us -- up the new bridge, puffing along that gigantic arc right to the top, queasy and giddy with the cars whooshing past and the slow river moving under you. Don't forget to turn around and look back! Those minuscule palm trees and baby park benches, all that glittering water, look like an architect's model, don't they? Now it's just a straight slide down to the beach. A cold beer's waiting for you on the pier at Benny's.