Improvised Cities: Architecture, Urbanization, and Innovation in Peru is a welcome addition to the growing scholarship on post-war modernism in Latin America. Gyger's work captures the vitality of a moment when the hopes of modernist architects strained against the economic realities of Peruvian society. It was in this period that Peru emerged as an epicentre for aided self-help housing in the Americas. Both pragmatic and participatory, the movement's call to combine technical assistance with the labour power of residents themselves resonated with architects and planners throughout the global south. This history, along with urban housing in general, is largely uncharted territory in Peru's historiography, a prospect that contains both promise and peril. Covering three different cities (Lima, Arequipa and Chimbote), expanding out to the United Nations, and tracing the storied careers of architects John F.C. Turner and Diego Robles becomes unwieldy at times. However, Gyger's wide-ranging approach ultimately proves to be illuminating by utilizing self-help housing as a central thread to hold this broad, ambitious narrative together.

The book begins with an overview of the key debates responsible for shaping Peru's urban housing policies in the 1950s. Despite the chaotic and complex nature of Lima's rapid urbanization, Gyger masterfully distils the swirl of debates into two central figures: Pedro Beltrán and Fernando Belaúnde Terry. The author draws on architectural journals and press coverage to analyse how the conflicting views of state-led developmentalism (Belaúnde) and free-market liberalism (Beltrán) were concretely expressed among Peru's most eminent urbanists. In Gyger's fascinating account of Belaúnde's earlier, more idealistic years (he later became Peru's president between 1963 and 1968 and again from 1980 to 1985), the influential architect envisioned a Peruvian metropolis composed of modernist neighbourhood units modelled on Inca territorial planning and Ebenezer Howard's garden city movement. With remarkable depth and sophistication, Gyger demonstrates how these visionary plans were overshadowed by the accelerated growth of Lima's informal shantytowns (barriadas). While the disjuncture between the ‘ideal city’ and the ‘barriada city’ is highlighted, the book would have benefited from a more conclusive synthesis of the relationship between these two forms of mass housing.

The book's historical analysis of John Turner is arguably its strongest feature. As Gyger contends, ‘It is through this singular figure that Peru and self-help housing…became legible to the larger world of architectural discourse’ (p. 95). Indeed, Turner's work in Peru (1957–65) provides a crucial link between Peru's local experiments in self-help housing and their incorporation into international aid packages financed by the Alliance for Progress. Due to Gyger's unprecedented access to Turner's personal archives, the reader is able to gain a vivid sense of life in Peru's sprawling barriadas (Villa El Salvador, El Ermitaño). The significance of the archives is not lost on the author as the volume features several stunning photographs of land invasions and self-built homes on the outskirts of Lima and Arequipa. Along the way, we follow Turner's career as he moves through Peru's intellectual circles (Eduardo Neira Alva, William Mangin) and international spheres (World Homes, Inter-American Development Bank, PREVI).

In the concluding chapters, aided self-help housing continues to function as an interpretive lens for the state's role in Peru's transition to an urban society. Chapters 7 and 8 encompass the years of Peru's leftist military regime (Revolutionary Government of the Armed Forces, 1968–80) and its neoliberal turn, most clearly articulated by economist Hernando de Soto. For General Velasco's revolutionary government, aided self-help housing provided a vehicle for the state to mobilize the masses into a movement for national development; for de Soto, it promised to liberate the informal poor from the weight of state bureaucracy in order to allow their latent, entrepreneurial spirit to flourish. The book's detailed account of housing programmes under the military's Revolutionary Government highlights an overlooked aspect of Peru's ‘peculiar revolution’ and should be of particular interest to scholars of this much-debated period in Peruvian history.

To date, Improvised Cities is the most comprehensive work on urban housing in Peru. As it moves effortlessly across various scales, Gyger reveals how transnational forces shaped Peru's mid-century housing programmes in a period rife with political volatility. While the book extensively documents various transnational influences within Peru, there is less attention paid to Peru's influence on the world of architecture and housing. Where does Peru's grand experiment with aided self-help housing stand in the broader context of Latin America's urban history? To what degree did aided self-help housing mark a rupture with practices before the 1950s both domestically and internationally? Improvised Cities will prove to be indispensable in answering these key questions, along with any future research on Peru's urban history and scholarship on housing in the post-war era.