RECOMMENDED ROUTE

Lucca is for walking. The longest diameter between the old walls is barely a mile, and it is easy to see a great deal in a day merely by meandering along the gray flagstone streets, while the buildings on either side merge from medieval to Romanesque to Renaissance to neo-classical and back again.

The purposeful walker can choose among three well-signposted ''tourist routes'' or plot his own course. All you need to do is to pick up a map at the tourist office in the center of town at 40 Via Veneto, and set off. The walk described below can take the best part of a day.

Lucca's streets still follow their original Roman layout. Go up Via Veneto from Piazza Napoleone (where you have probably parked) and start at the church of San Michele, built on the site of the old Roman forum. The main part dates from the 12th century; In the spandrels, green mosaic huntsmen, hawks and hounds chase stags, hares, boars and bears, while lions and dragons fight each other - a medieval bestiary in stone. Many of the capitals bear 19th-century additions - notably the carved heads of such heroes of the Risorgimento as Garibaldi, Vittorio Emanuele, Cavour and Napoleon III.

Leave the Piazza San Michele by its southwest corner, walking west along Via San Paulino. (Note that as you leave the square by this route, just off to the left, at 1/5 Via della Cervia, is Buca di San Antonio, a restaurant worth a detour from wherever you are when serious hunger strikes.) At the end of Via San Paulino, turn right into Via Galli Tassi and stop at the 17th-century Palazzo Mansi on the left.

Do not be fooled by the simplicity of its exterior. Inside is an elegant palace built around courtyards with shady loggias. The rooms themselves are opulent illustrations of the ancient wealth of Lucca. They culminate in a wildly rococo Wedding Room with a huge canopied bed hung with elaborately embroi- dered silk, set into an alcove created by a heavily carved and gilded arch supported by man-high gilded caryatids.

Continue up Via Galli Tassi, turn right on Via San Giorgio and continue to Via Fillungo where you turn left. This is Lucca's main shopping street, from which traffic is banned. Boutiques on either side display the best French and Milanese ready-to-wear and Florentine leather, supple and lusciously colored. There are jewelry shops galore, many with interiors frescoed and decorated with gilded plasterwork that make them small gems in themselves.

At the Piazza Scarpellini ignore, for the moment, the sign on the right pointing to ''Anfiteatro Romano Sec. II'' and, instead, turn left for the austere Romanesque Basilica of San Frediano, named after an Irishman who was bishop of Lucca in the sixth century. After visiting the austerely Romanesque interior, return to the Piazza San Frediano, cut down Via Anguillara and then up Via Fontana. The former is lined with the simplest of shuttered houses, some punctuated by Renaissance iron window grills. At the end of Via Fontana is Via Battisti, with several modestly Baroque palazzi. One, the Palazzo Pfanner, is worth a visit for a look at its formal, 18th-century Italianate garden with statuary and fountain. Then go up the palazzo's outdoor staircase to the second floor where there is a small but attractive collection of 18th- and 19th-century Lucchese costumes.

Return to Via San Giorgio by continuing down Via Battisti away from San Frediano. Turn left and you arrive back at Via Fillungo. You are now heading for the Roman amphitheater, but this route gives you another chance to window shop the boutiques.