Restaurants in Harvard Square seem to come and go almost as quickly as graduating classes.

BUSINESS

Suddenly, Square residents awoke to find One Potato, Two Potato replaced by the Grafton Street Pub, Ultimate Bagel became Toscanini's and 8 Holyoke was now Sandrine's.

Behind the ever-changing Square restaurant scene are management, location and the nature of the restaurant business.

From diners to bistros, Harvard Square has changed from blue collar to top dollar, following the tastes of its residents.

In the Past

Thirty years ago, Harvard Square shops catered to the working-class. Launderettes and shoe repair shops abounded.

The restaurants were much the same.

Formica tables and vinyl booths attracted customers from the nearby MBTA maintenance shops; beer, sausage and corned-beef sandwiches were the extent of the menus.

But the late 1960s was a tumultuous time for the nation, and it was no different for Square restaurants.

As students flooded into Harvard Square, then a center of activism, restaurants began catering to younger crowds.

"At that time, a lot of shops began to change from being sort of neighborhood shops to having a specific appeal to young people," says Charles M. Sullivan, director of the Cambridge Historical Commission and 33-year Cantabrigian.

And as lunch counters like the Waldorf and theMug n' Muffin started to close their doors,restaurants aimed at students took their places.

"They were a little funkier and a littlecuter," Sullivan says. "Definitelystudent-oriented."

The trend continued through the next decadesuntil the present.

Today, the days of diners are dwindling as NewAmerican bistros put tomato coulis where good oldketchup once stood.