Casanova's Venice is a city of intrigue and extravagance, a fitting homeland for a multi-faceted, extravagant man. The foremost scoundrel of the 18th century was also a memoirist of formidable talent. In the fourth volume of his autobiography, Casanova -- who was, variously, a spy, a diplomat, a soldier, an astrologer, and a cleric -- tells of his imprisonment in the dungeon of the Ducal Palace in Venice. The tale made him a wanted commodity throughout Europe in 1756, the year of his escape, and indeed it is no less sensational now.  (ITL381, $25.00)