During the summer of 1895, Per Olof Hallman, a young Swedish architect, embarked on a study trip through Germany, Austria, France, and Belgium. This article investigates the underexplored, formative phase of Hallman’s career, focusing on how his exposure to European best practices and theoretical influences, particularly from Camillo Sitte, Joseph Stübben, and Karl Henrici’s 1891 plan for Munich, shaped his unique approach to city planning. It addresses the origins and reception of his early ideas by analysing materials from Hallman’s underexamined personal archive through the theoretical framework of travelling ideas. Upon his return to Sweden, Hallman began advocating for a more dynamic and aesthetic approach to city planning, departing from the dominant method of flattening terrains to accommodate rigid, chessboard-like street layouts. He challenged the prevailing focus on practicality at the expense of aesthetics, instead promoting the integration of natural elements such as terrain (including slopes, elevation, and undulations), wooded areas, waterways, and greenery, along with artistic principles to create more historically informed and liveable urban environments. This journey marked the starting point of his progression from a student of architecture to a pivotal figure, albeit one who is nowadays largely overlooked. The paper underscores Hallman’s role in facilitating the transfer of travelling ideas and the lasting impact of his input on the establishment of city planning as a discipline in Sweden.

At the turn of the twentieth century, the young Swedish architect Per O. Hallman emerged as an advocate for artistic city planning approaches. Inspired by St & auml;dtebau philosophies, Hallman viewed city planning competitions as crucial platforms to advance these innovative ideas, advocating for them as a counterpoint to the prevailing chessboard planning methods driven by engineers and land surveyors. His ideas resonated beyond Sweden, also diffusing into Finnish professional circles. This resulted in competitions for the unplanned districts of T & ouml;& ouml;l & ouml; in Helsinki (1898-1902) and southern Gothenburg (1901) - the first occurrences in Finland and Sweden to adopt artistic principles. Although Hallman served as a key agent for diffusing Camillo Sitte's principles from the Continent, his contributions remain underexplored within international city planning scholarship. The article addresses this gap by examining Hallman's largely untapped archival materials, which shed new light on his cross-collaborations with other prominent figures, including Fredrik Sundb & auml;rg, Bertel Jung, Lars Sonck, and even Josef St & uuml;bben, with whom he worked closely and judged the second stage of the T & ouml;& ouml;l & ouml; competition. Through these collaborations, Hallman not only advanced his own planning approach but also facilitated the breakthrough and integration of artistic values into city planning across two of the Nordic countries.

City planning expositions in the early twentieth century played a significant role in shaping urban policy across Europe, including Sweden. Events such as the St & auml;dtebau Exhibitions in Dresden (1903) and Berlin (1910), and the London Town Planning Conference (1910), became key arenas for the circulation of planning ideas. These forums enabled a two-way exchange of knowledge: Swedish delegates absorbed international models while also presenting domestic planning approaches and legislative frameworks that drew interest abroad. This exchange helped position Sweden not merely as a recipient but as an active contributor to transnational city planning debates. Architect Per O. Hallman was among the Swedish delegates who actively participated in these expositions. Although his role has received little attention in international planning historiography, his involvement reflects how Swedish planners engaged in a wider transnational dialogue. Drawing on underexplored archival sources, including Hallman's correspondence with figures such as Reinhard Baumeister, Josef St & uuml;bben, Theodor Goecke, and Raymond Unwin, this article traces how international exhibitions supported the circulation of planning knowledge. It argues that Sweden's engagement in these forums reflected and contributed to broader international planning debates, which helped align national planning approaches with emerging European developments.

This article examines how early twentieth-century Swedish city planners transformed domestic urban design by actively engaging with transnational professional networks. Moving beyond isolated pioneers, it analyzes a collaborative cohort including Anders Nilsson, Fredrik Sundbärg, Per O. Hallman, Albert Lilienberg, and Nils Gellerstedt. To counter rigid gridiron planning favoured by older engineering establishments, they adapted artistically and topographically sensitive ideals from the German-speaking area before shifting toward reformist British town planning models. Using a microhistorical approach grounded in archival research of surviving correspondence and professional records, the study maps their development across three distinct tiers of professional maturity: theoretical introduction via study trips, practical adaptation through planning competitions, and international dissemination at large-scale public exhibitions. Tracing these specific interpersonal and institutional channels demonstrates exactly how Swedish practitioners successfully evolved from passive recipients of continental concepts into highly active contributors to a bi-directional, transnational exchange of urban expertise.