The recognition during the second half of the 20th century of the essential role played by public spaces in the definition of qualitative urban life has led to a reconsideration of their design. This has occurred in many different forms, such as the emergence of new profiles of designers, the valorisation of new types of places or the awareness of new uses. But more surprising is the remarkable diversification of formal and material specificities that have emerged since the turn of the 21st century, as well as the manifestation of new design references. These evolutions seem to lead to a singularisation of public spaces in the urban fabric. Within only a few decades, the field of public space design has gone through a profound transformation. However, the impact of these evolutions on cityscapes has not been substantially questioned so far. The lack of critical studies dealing specifically with design processes is particularly striking. The aim of this research is to fill this gap by taking a critical look at contemporary public space design. To engage in the practice of a critique requires going through four essential steps that will structure this work: First, a general portrait of the contemporary production of public spaces needs to be established in order to extract main design trends. Genesis, the first part of this thesis, presents the development since the 1980s of evolving thoughts on public space design. The aim of a critique is to verify a predefined theory. Therefore, in the second part, we hypothesize the idea of a formal, material and semantic singularisation of recent public spaces, according to the theory of a public space designed as an object per se. The development of this research is dedicated to verifying this change of position. The third step consists in conducting a series of critical analyses of a corpus of fourteen study cases, in order to verify our theory. The question of design intentions is looked into by a novel method of critical analysis, comprising a genetic study of projects. Finally, the fourth step entitled comparative reading consists in identifying recurring and representative design positions. This comparative reading confirms the idea of a detachment from the urban material context in recent designs. It also reveals three factors explaining such a singularisation: (I) the consideration of public space designs as salutary projects capable of revitalizing depreciated urban contexts; (II) an extended interpretation of the notion of context; (III) the perception of contemporary public spaces as potential vectors of urban experiences. These three evolutions of thinking have direct consequences on the design of public spaces. They produce a climate of experimental freedom that designers harness with interest, leading to a strong singularisation of public spaces. These evolutions also explain the outbreak of new design idioms with a strong narrative dimension, which no longer refer to tangible and adjacent contextual elements. Finally, they lead to a decrease of site-specificity in the designs that respond to universal principles of perception and frames of reference. A tendency to singularise current public space designs and, in an almost contradictory manner, to universalise them simultaneously, seems to appear. These trends contribute, in our view, to creating public spaces as objects per se, by designing them as autonomous and transposable at once.