In the summer of 2007, during work to restructure the building at No. 45-46 via de’ Ciancaleoni in the Monti quarter, the Archaeological Superintendency of Rome ordered investigations to be undertaken in the basements. The removal of the modern debris (datable to between the first decades of the 20th century and the present) inside the cellars accessible from No. 46b revealed numerous rooms in _opus reticulatum_ with barrel vaulted roofs. These were part of a late Republican house ( _domus_ with _atrium_ and peristyle). More rooms of the same _domus_ together with others from an adjacent house, accessible from via Cimarra No. 37, were investigated in 1969-70 by V. Santa Maria Scrinari and published by A. M. Ranieri. The 2007 investigation thus provided a fuller picture of the residential complexes covering an area of circa 700 m2. It was possible to distinguish the earlier house (circa 50 B.C.) which was flanked by the second _domus_ around the beginning of the second half of the 1st century B.C. The latter was characterized by two parallel _cryptoporticus_ between which there were a series of symmetrical rooms mirrored by a second series. During the 1969-70 investigations the remains of wall paintings in the II style emerged together with mosaic floors. Both dwellings, which constituted a sort of terracing on the hill slope, were on an east-west alignment and at a right angle to the _via Patricius_. The location, size and state of preservation of the structures also made it possible to formulate a number of hypotheses regarding the urban development of Rome near the eastern slopes of the Viminal in the late Republican and early Imperial periods. At present it appears that there was no large scale construction in the area between via Cimarra and via de’ Ciancaleoni, where the above structures were found, until the end of the 1600s or the beginning of 1700 and that a part of the structures were used as a wash-house in the modern period.