THREE OR FOUR YEARS AGO, Harvard Square was a center of Movement culture--a gathering place for a New Left politicos, an arena for folk and rock concerts and street theatre, and a staging ground for protests and periodic riots. Since then the Square has become commercialized, the radicals have been arrested or become quieter, and much of the Movement has moved away from the more pastoral surroundings.

But a residue of times gone by remains. Strung-out freaks panhandle, play music or sit and talk in front of Holyoke Center. Streethawkers confront passersby with Boston's two youth-oriented weeklies, The Phoenix and Boston After Dark. Tourists crowd the shops and streets and restaurants on weekends and sunny days.

Other trends in the Square continue stronger than before. Centuries-old traffic patterns--a city planner's nightmare--cause bumper-to-bumper line-ups on side streets as well as main thoroughfares. Old storefronts fall and are replaced by the modern facades of state or nation-wide retail chains. High-rise buildings make way for office space, apartment dwellers and the trappings of modern commercial affluence.

While the Square is no longer unique, it still remains unusual, if only because it orients itself towards a young, semi-intellectual audience. This article is humbly offered as an aid to the physical layout of the area, a recommendation of some places worth going to and things worth seeing, and a warning on which places would be better avoided.

Snacks

Few students will get through the first week's bill-of-fare at the Union without a strong sense of gastronomic restlessness. And the Square's many eateries are ready to oblige Harvard's hungry or nauseous.

If what you want is sandwiches, the best places are Elsie's (at Mt. Auburn St. and Holyoke St.) and Tommy's (60 Mt. Auburn St.). Elsie's specializes in huge delicatessen sandwiches; Tommy's has subs, good pinball machines and a jukebox. Hazen's (next door to Elsie's) isn't as good, but has more counter space and booths to sit down in.

For more expensive sandwiches, and a much larger menu to choose from, try the Midget Delicatessen (1712 Mass Ave, near the Radcliffe dormitories). The Mustard Cup, across the street, has great cheese cake. Roy Rogers (1613 Mass Ave) is worth avoiding unless you like pre-processed roast beef and the atmosphere of a McDonalds.

The roast beef at Hungry Charlie's (right in the Square) is not much better, but Charlie's apple beer, served in a tall mug, is worth trying.

If you're after hot dogs, the Square offers two restaurants devoted to them. Newly opened (and prone to flooding on rainy days) is the Underdog (6 Bow St.), which has kosher dogs with assorted garnishes. The Underdog also has good bagels with cream cheese and lox. Zum Zum (9 Brattle St.), part of a small East Coast chain, serves knackwurst, bratwurst and bauernwurst, with very tasts potato salad. The dark beer is really good.

Hamburgers can be had in nearly any shape or form at Barley's Burger Cottage (1246 Mass Ave). Starting from the basic Bun 'n' Burger, Bartley escalates to the Muenster Cheeseburger, the Super Pizzaburger, the Hawaii Pineapple Burger, the Texas Chiliburger and on ad nauseum.

If your palate cries out for something more exotic than hamburgers and hot dogs, try the Hungry Persian (52 Boylston St.). The Persian serves its sandwiches in hot Syrian bread, and the contents--mostly sliced and shredded cold cuts--are flavored with tahini sauce and have a refreshing Middle Eastern taste. For less than a dollar your empty stomach can be satisfyingly filled. The baklava is delicious.

There are three pizza parlors in the Square, all of which serve their product with the normal options on demand. They are Joe's (at the corner of Mass Ave and Linden St.), the Pizza Pad (at the corner of Mt. Auburn St. and Plympton St.) and Pinnochio's (74 Winthrop St.). Joe's seems to be the favorite of most Harvard students.

The Square also has its share of ice cream parlors. Some have standard fare, like Brigham's (next to the Coop) and Bailey's (21 Brattle St.). Others are a little more exotic, like Baskin Robbins (1230 Mass Ave) which has 31 flavors, and the Spa (0 Brattle St.), which serves frozen yogurt.

For late breakfasts, try the Pewter Pot (3 Brattle St.), which has excellent muffins, or As You Like It (1326 Mass Ave). As You Like It has good eggs and sausages, and big cups of hot chocolate, but not much else worth eating. Nornie B's (61 Church St.) has good donuts.