The story of Romulus and Remus is almost as old as Rome. The orphan twins were suckled by a she-wolf in a cave on the banks of the Tiber. Romulus grew up to found Rome in 753 B. C. Historians have long since dismissed the story as a charming legend.

This year, Italian archaeologists reported discovering the long-lost cave under the Palatine Hill that ancient Romans held sacred as the place where the twins were nursed. The grown brothers fought over leadership of the new city, the story goes, and Romulus killed Remus and became the first king.

The cave was no surprise to Andrea Carandini, a historian and an archaeologist at the University of Rome, who has said, ''The tale of the birth of Rome is part myth and part historical truth.'' He had already found remains of an ancient wall and ditch and also ruins of a palace that he said was built in the eighth century B.C.

''When I excavated the Romulean-age wall on the Palatine, I realized that I was looking at the very origins of Rome as a city-state,'' Dr. Carandini said in a long interview in the July-August issue of the magazine Archaeology.

Dr. Carandini said the wall, built on the slopes occupied by huts of the pre-Roman settlement, was dated through a number of foundation deposits to about 775-750 B.C. He said that the wall was possibly the sacred boundary in Rome's foundation legend and concluded that it was ''archaeological evidence of the existence of Romulus and Remus.''