This study investigates the effect of building height regulations in Seoul, South Korea, leveraging the city's unique urban landscape and planning policies. Seoul's distinct centers, Gwang Hwa Mun District and Teheran Ro District, serve as contrasting case studies for assessing the effects of height regulations. In Gwang Hwa Mun District, Seoul's historic center, stringent height caps were implemented to preserve its cultural heritage. In contrast, Teheran-Ro District, conceived as a modern financial hub, features minimal height restrictions aimed at promoting economic growth. Using a 'stringency' to quantify the degree of deviation between regulated and free markets, we compare the strict regulations of Gwang Hwa Mun (stringency index: 0.124) with the more lenient approach in Teheran-Ro (stringency index: 0.091). Our analysis reveals that Gwang Hwa Mun faces stronger regulatory constraints, resulting in higher real estate development costs compared to Teheran-Ro. This study underscores the significance of Seoul's dual approach to building height regulation in shaping urban development patterns and highlights the trade-offs between heritage preservation and economic progress. HighlightsInvestigate the effect of building height regulations using 'stringency' to quantify the degree of deviation between regulated and free markets in Seoul, South Korea.Comparing the two centers of Seoul, Gwang Hwa Mun and Teheran-Ro districts, reveals that the historic center has a higher stringency of 0.124, whereas the master-planned CBD has a stringency of 0.091.Gwang Hwa Mun is governed by stricter regulations than Teheran-Ro, preventing the construction of higher buildings in the historic center and resulting in higher real estate development costs compared to Teheran-Ro.