A paved trapezoidal area with the plinth of a puteal which marks the spot of the legendary Lacus Curtius in the Forum was discovered in April 1904. The name is derived from the legends of its origin, which refer either to the Sabine Mettius Curtius, or to the Roman youth Marcus Curtius who sacrificed himself, or else to the consul C. Curtius (B.C. 445) who, by order of the senate, enclosed the spot when it was struck by lightning. The pavement of Monte Verde tufa slabs, which is still visible below the travertine pavement of the imperial Forum, dates from the time of Sulla.
The sacred precinct of Iuturna, which lies immediately south-east of the three upright columns of the Temple of Castor, was excavated early in 1900. The complex consisted of the Lacus itself, an aedicula for the statue of the goddess, and other rooms, which, from the early part of the 4th century, were used by the statio aquarum, or headquarters of the Rome water service. According to legend, the Dioscuri watered their horses at the spring of Iuturna after they had brought news of the victory at Lake Regillus, in 496 B.C. Their statues were found in the basin, badly broken. They probably stood on the north side of the Lacus, in a small sanctuary which is recognizable on a fragment of the Severan marble plan.
The fountain in the south-west part of the Forum, known as the Lacus Servilius, became famous at the time of Sulla, for it was there that the dictator exhibited the heads of the Senators he had ordered to be executed. Agrippa decorated the fountain with the statue of a Hydra. According to Festus (290), it was situated "in principio vici Iugari continens Basilicae Iuliae." At this point, where the vicus Iugarius meets the Sacra Via there is, between the steps of the Basilica Iulia and the buttress of the vicus Iugarius, a cavity which could have contained a fountain of modest dimensions (6.70 x 2.50 m.). The water was supplied by a conduit which branched oft the Aqua Marcia behind the Temple of Saturn, on its way from the Quirinal to supply the Capitol. It was drained off into a channel which ran under the steps of the Basilica Iulia and into the Cloaca Maxima.
In January 1899, a square of black marble paving was discovered between the Comitium and the Forum, which Festus (177) and other Roman writers refer to as the Lapis Niger, or the Tomb of Romulus. In May of the same year, a group of archaic monuments was found beneath it, consisting ot a foursided stele with inscriptions (CIL VI, 36840), the stump of a conical column, and the foundations of a sacellum, with tufa bases in front of it which may have supported the statues of recumbent lions. Even in antiquity the meaning of these monuments was unknown. The so-called tomb was attributed not only to Romulus, but also to his foster father, Faustulus, or to Hostus Hostilius, the father of King Tullus. The excavations were resumed in 1955 and have confirmed that there is no tomb under the Lapis Niger.
The Ludus Magnus was the principal training school for gladiators; it was known from the Regionary Catalogue and from inscriptions, as well as from fragments of the Severan marble plan, even before 1937, when part of the building was discovered between Via Labicana and Via di S. Giovanni in Laterano, about 60 m. east of the Colosseum. In the centre of a portico, an eliptical practice ring with two entrances, in the long and cross axes respectively, was surrounded by a narrow belt of low seats, arranged in tiers. The portico was enclosed in the multi-storeyed, rectangular building of the barracks.