The Roman Forum for centuries was the ancient Romans' point of reference in terms of the law, religion, and social life. Also known as Forum Magnum or simply Forum, it was located in the little valley between the Palatine Hill and the Campidoglio.
Originally used as a necropolis, it was later the battle theatre of Lake Curzio, hosting combats between the Romans and Sabines. Such was documented by the Roman historian Livy.Roman ForumAccounts narrate Tarpeia's betrayal of Rome (Tarpeia was the daughter of Spurius Tarpeius, commander of the Roman citadel). After Titus Tatius turned her, she allowed a group of armed Sabines to enter the stronghold, which led to a Roman front taking over the Campidolgio, the Sabines, the Palatine. It is said that Romulus - Rome's founder according to the mythology - launched into an attack on his enemies. By doing this, he angered the god Jupiter, and promised him to build a temple to him in exchange for a victory. (The Temple to Giove Statore was later built in the vicinity of the Forum). The battle eventually ended with a peace agreement between the two populations, but not until the Sabine women intervened by separating their Sabine fathers from their Roman husbands. After, in diverse historic epochs, the Roman Forum continued to add new structures and monuments to its "collection." 

During Rome's Monarchy (6th Century B.C.), Lapis Niger was an area paved in the black stone linked to the myth of Romulus's death, while the Regia or Royal Palace was where the Rex Sacrorum (the patricians' senatorial priesthood) and the highest pontiff exercised their religious functions. Finally, the Temple of Vesta was the highly-revered sanctuary dedicated to the goddess of hearth and home.
Then, dating back to the Republican period are the Tabularium, a public records building; and four Basilicas (Porcia, Aemilia, Sempronia and Opimia), purposed for the administering of justice and citizens' affairs.  

The Imperial period saw the construction of the Temple to Divo Giulio or Divine Julius, and the Temple of Concord, erected on occasion of peace between the plebeians and the noble classes.

During the Medieval and modern eras, unfortunately, the Roman Forum was destroyed and fell into further decay. Most of the Forum's monumental spaces were surrounded by Medieval fortifications, and some even became grazing pastures and agricultural cultivations. And the Renaissance - with the hand of Pope Julius II - brought the destruction of other temples and sanctuaries, leaving the Forum as a mere trash quarry of materials to be re-used for more modern constructions.