In the eighteenth century, a degree of continuity existed between the fields of pictorial and architectural création. This thesis sets out to situate Hubert Robert within this milieu, as a painter who could conceive complex imaginary architecture - and often integrate it with landscape - in order to produce appealing images. Its leading argument is that the questions raised by Robert and his contemporaries' représentations of architecture chiefly pertain to temporality. Several articulations of architecture and time are thus traced, including the relation of Robert's works to the writing of architectural history during his lifetime, a period that witnessed important évolutions in this field due to the documentation of many ancient sites that had hitherto remained little-known. The painter's own contributions to these publications are also studied, though much of his work does not simply deal with représentations of the past, but with more complex temporalities conflating différent periods and even investigating the future. The theme of ruins- besides arousing philosophical musings on vanity or the greatness of empires - thus led several thinkers of Robert's time to imagine a future Paris in ruins, a vision that resonates strongly with several of the painter's works. The latter, however, also interact with contemporary architectural création. This thesis thus demonstrates not only how Robert represents modem architectural forms in ancient contexts - thus granting them prestige and a form of historical legitimisation - but also how the artist's works lead several architects and urban planners to suggest projects for grand public spaces in Paris resembling Robert's visions of monumental antique cities.