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ITH WISDOM and hospitality, a formerPresident of Colombia urged his officialvisitors to see the antique city of Cartage- na de noche y en coche-a 
          rhyme in Spanish,"by night and by coach."   Romantic notion, and more: This fortress 
          city onthe Caribbean is a world heritage site, as designatedby UNESCO.  Like an aging beauty, Cartagena best 
          recaptures her voluptuous past in the dim light ofcandles and coach lamps.  To the cadence of horse | 
   
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        Mirrored in a street slickwith rain, a hired coachstands topsy-turvy beforethe Church of San PedroClaver in the romanticcolonial quarter of thishistoric Colombian city.A key port of the SpanishMain from the 16th to the 18th centuries, Cartagenaproudly preserves thegrand structures of that bygone era. |  
        gold, Cartagena became the most importantport in the New World, a storehouse for provi-sions and treasure and a fatal temptation for plunderers.   Now, by day, new parts of the city sprawl wide.Sunbathers, basted with lotions, carpet the beach.Vendors sell raspados-shaved ice with syrup-sea-shell jewelry, and garlands of fishy iguana eggs.Colombians from Bogotá-cachacos to the localfolk-come here "so they can stroll the streets in safe-ty," a young policeman says proudly.  "Here peoplemake love, not crime." So growing Cartagena bus-tles, newly noisy with 800,000 people.   Some 70,000 still live within the old battlements.And each afternoon they await "that hour of mysteri-ous flourishing, " as poet Guillermo Valencia calledit.  Like an unlucky ship, the sun slips abruptly intothe sea.  A strong, steady breeze blows in, rattling |