Low understanding of geometric concepts remains a persistent challenge in mathematics education, particularly in connecting abstract ideas to real-world situations. Traditional, abstract instruction often causes students to struggle with understanding, applying, and relating geometric concepts to their immediate environment. Although various studies have explored ethnomathematics within Madurese culture, research analyzing students' geometric understanding through the architecture of the Madurese Traditional House (Taneyan Lanjheng) remains limited. Therefore, this study aims to analyze students' comprehension of geometric concepts using an ethnomathematical approach embedded in Taneyan Lanjheng architecture.Employing a descriptive qualitative approach, this research was conducted at MTs Nurul Irsyad Gondanglegi, Malang Regency. The subjects comprised 10 eighth-grade students, from which six key subjects were selected to represent high, medium, and low academic abilities. Data were collected through observation, written tests, semi-structured interviews, and documentation, and subsequently analyzed using the Miles and Huberman framework (data reduction, data display, and conclusion drawing).The findings reveal that students' understanding of geometric concepts varied significantly by ability level. High-ability students successfully restated concepts, selected appropriate procedures, and applied geometric ideas within the architectural context of the Madurese Traditional House. Medium-ability students demonstrated basic understanding but made procedural errors, whereas low-ability students struggled to comprehend concepts and connect them to cultural artifacts. Overall, these findings indicate that an ethnomathematics approach fosters more contextual learning, thereby enhancing geometric understanding. The practical implication suggests that leveraging local culture as a learning resource serves as an innovative alternative for meaningful mathematics instruction, while future research may extend this approach to other mathematical concepts and cultural contexts.