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In the village of Rupingrande, a mile and a half away, the Museo della Casa Carsica (closed Mondays) preserves traditional articles of daily life in the area. Some of the nearby houses have rustic stone doorframes with engraved religious symbols, and inscriptions in Slovenian.

At Prosecco, two miles from Rupingrande, look for signs pointing toward the Strada Napoleonica - also called the Strada Vicentina - now reserved for pedestrians. You can park your car at the bottom of a cliff emblazoned with Napoleon's imperial coat of arms and stroll for miles, enjoying the view of Trieste and the Gulf. From Prosecco head northwest three miles to Santa Croce, then descend to the coastal road (S. S. 14) and proceed eight miles to Duino. An unauthenticated tale has it that Dante spent some time as a guest in the village's early medieval castle, the ruins of which occupy a promontory. What is certain is that the Castello Nuovo (''new'' in this case meaning 14th century) above it sheltered a later poet: in 1911-12 Rainer Maria Rilke was a guest of Princess Maria von Thurn und Taxis-Hohenlohe, whose family has owned the castle for 400 years, and while walking through the nearby woods he conceived the ''Duino Elegies.'' Visitors may hike along the panoramic passeggiata di Rilke, as the path is now known, and rent rowboats at the pier below.

The castle is not open to the general public, but its current occupant, Prince Raymond von Thurn und Taxis, frequently hosts cultural and scientific congresses. Since 1982 the guest wing has housed the United World College of the Adriatic, one of seven U. W. C.'s located throughout the world. The organization's president is the Prince of Wales, and its declared aim is to combine ''high-quality academic study with activities which encourage a sense of adventure and social responsibility.'' Two hundred high-school-age students from more than 50 countries are enrolled in the Duino school; all are given full scholarships, including room and board. Further information is available through the U. W. C.'s International Office, London House, Mecklenburgh Square, London WC1N 2AB.

Barely a mile beyond Duino, at Bocche del Timavo, the little Timavo River ends a 25-mile underground journey and bursts forth - or trickles out, depending on the time of year - to flow directly into the sea nearby. The site was sacred to ancient peoples and is mentioned by Virgil and Livy; pre-Roman artifacts have been discovered here, and Roman inscriptions are set into the walls of the 15th-century Gothic church of San Giovanni del Timavo, on a knoll beyond the Bocche. Much of this building had to be reconstructed after World War I, and shell holes are still visible in the outside walls.

World War I seems increasingly, tangibly present as you head inland along S. S. 14 and 305 (switch to 305 at the industrial town of Monfalcone, two miles past the Timavo). Italy's main reason for entering the war was to wrest this area and the Trentino, both of which had Italian ethnic majorities, from Austro-Hungary; some of the bloodiest confrontations between the Italian and Austrian armies took place in Friuli-Venezia Giulia (the setting of Hemingway's ''A Farewell to Arms'').

Italy won the territory but lost 600,000 men in the effort. The military cemetery at Redipuglia, two miles beyond Monfalcone, is the biggest and most pretentious of the war memorials. Created by Italy's fascist regime in 1938, it reminds one more of Mussolini's nationalistic rhetoric than of the 40,000 identified and 60,000 unidentified soldiers buried there. A vast set of steps stretches up and up, and on each tier the word ''PRESENTE'' is repeated ad infinitum.

The village of Sagrado - with a fine restaurant, Bella Trieste - lies on the south bank of the Isonzo River, a mile past the cemetery. Twelve major battles were fought along the Isonzo during World War I; on a nearby hill, Monte San Michele, 112,000 Italian soldiers and great numbers of Austrians were killed between September 1916 and June 1917. You can visit the Italian Third Army's trenches, carved into rock.

IMMEDIATELY after crossing the Isonzo at Sagrado, turn right on the road to Gradisca d'Isonzo, a mile away. This fortress town - ''grad'' means fort in Slovenian - was used by the Venetians against the Turks in the late 1400's, by the Austrians against the Venetians in the following three centuries, by Napoleonic France against Austria, by Austria against 19th-century Italian nationalists and by everyone against everyone else in the two world wars. Despite its militaristic history, its massive walls and the remnants of its once-forbidding castle, modern Gradisca is a gracious town with a vast, chestnut-tree-lined public square, pleasant cafes and elegant little baroque and rococo palaces: the Corona, the Strassoldo and the Fin-Patuna, where General Bonaparte spent a night in 1797, and the stately Torriani - headquarters, in 1813, of Napoleon's stepson, Prince Eugene de Beauharnais, Viceroy of Italy. Palazzo Torriani now houses an art gallery with a permanent display of works by a local painter, Luigi Spazzapan, and temporary exhibitions dedicated to internationally known artists.