QUESTION: We will be in Italy in March and would like to know if the Ferrari and Maserati factories in Modena have tours.

ANSWER: Maserati gives tours by appointment on Monday, Wednesday and Friday after 5 p.m. English-speaking guides are available.To make arrangements contact Maserati Automobili, 322 Via Ciro Menotti, 41100 Modena, Italy; telephone from the United States 217160. Fax: 219669.

The country code for Italy is 39; when calling from within Italy, precede the city code with zero. The company requests a letter or fax requesting a specific date.

Tours of the Ferrari plant are available only for those Americans who have purchased a Ferrari from a dealer. The Ferrari owner contacts the dealer who makes arrangements through Ferrari North America, which is in Englewood Cliffs, N.J.

QUESTION: I am planning a visit to Dublin in mid-March and would like to view the Irish Parliament in session.

ANSWER: The Irish Parliament, known as the Dail, sits on Tuesday from 2:30 to 9 p.m., Wednesday from 10:30 A.M. to 9 P.M. and Thursday from 10:30 a.m. to 5 p.m. It goes into recess for July through September, for about three weeks at Christmas and three weeks at Easter, probably the last week in March and the first two weeks in April this year.

Visitors who wish to attend a session at the Dail should either write to the Captain of the Guards, The Dail, Leinster House, Dublin 2, Ireland, or telephone the Captain of the Guards at in Dublin at 789 911. (The country code is 353 and the city code is 1 from the United States and 01 in Britain.)

QUESTION: Do you know of a flea market in or near Paris?

ANSWER: The Marche aux Puces, in St.-Ouen just over the northern boundary of Paris, is by far the biggest flea market in the area, with more than 2,500 shops and stalls in several buildings over 23 square blocks.

Though the name means flea market, it features fine antiques and designer furniture, along with traditional flea-market bric-a-brac. Among the sections of the market, the March'e Vernaison at 99 Rue de Rosiers and 136 Avenue Michelet offers Second Empire furniture, English furniture, silver, objets d'art, toys and dolls.

Marche Paul-Bert, at 16 Rue Paul-Bert, sells Art Deco and turn-of-the-century antiques. Marche Jules-Valles, with entrance at 5 Rue Jules-Valles, has Art Deco objects, old photos, toys, postcards and gadgets. March'e Mailik (60 Rue Jules-Valles) has vintage clothing.

The market is open Saturday, Sunday and Monday, roughly from 7:30 a.m. to 7 p.m., though hours vary among shops, some of which close for lunch. Metro: Porte-de-Clignancourt.

The Vanves flea market on Avenue Georges-Lafenestre in the 14th arrondissement has a wide variety of items, including books, clothes, old photographs, toys and tableware.

It is open on Saturday and Sunday from about 7:30 a.m. to 7:30 p.m.; clothing stalls usually open in the afternoon. M'etro: Porte de Vanves.

The Aligre Flea market at Place d'Aligre in the 12th arrondissement, is in the midst of a larger market selling fruits and vegetables.

Its specialty is used clothing, though there is old china and silver, too. It is open from about 7:30 a.m. to 12:30 p.m. every day except Sunday. M'etro: Ledru-Rollin.

The Porte de Montreuil in the 20th arrondissement consists of sellers of antiques and secondhand books surrounded by vendors of cheap clothing and miscellany. It takes place on Saturday, Sunday and Monday from 7 a.m. to 5 p.m. Metro: Porte de Montreuil.

QUESTION: I am interested in exploring the Douro Valley of Portugal, perhaps during the harvest.

ANSWER: The grapes that produce port wine are grown in the section of the valley of the Douro River starting 62 miles upstream from Oporto and three miles south and 16 miles north along the river, to the border with Spain.

There is a concentration of vineyards from Peso da Regua eastward along the steep, terraced sides of the Douro and its tributaries.

The grapes are usually harvested in late September and early October. During the harvest, women and children pick grapes and the men carry large baskets of them up and down the steep slopes.

The grapes are no longer trod underfoot on a large scale, though some estates crush some that way for the benefit of tourists.

Information on visits to vineyards is available at the tourist office in Oporto at 25 Rua Clube dos Fenianos; telephone 312740.

In Peso da Regua a tourist office on Caldas do Moledo, (054) 23846, and one beside the train station on Largo da Estacao, (054) 22864, also have information. (The country code for Portugal is 351. When calling from inside Portugal, drop the initial zero in the area code.)

Tour companies in the United States experienced in travel to Portugal can arrange trips that will include air fare, accommodations in the port wine area and rental car.

One is Abreu Tours, 317 E. 34th St., New York, NY 10016; (800) 223-1580 or (212) 661-0555. The cost per person in double occupancy would be about $1,635 for a nine-day trip, the company says. Another company is Pinto Basto Tours, 280 Lafayette St., New York, NY 10012; (212) 226-9056.