This research was conducted to explore the Mpu Tantular Museum in depth by applying the concept of ethnomathematics. In this case, the researcher attempts to describe the real shape of the historical artifacts of the Mpu Tantular Museum using mathematical concepts. The type of research applied is qualitative research with an exploratory approach that focuses on the relationship between two-dimensional and three-dimensional geometric concepts with historical artifacts in the Mpu Tantular Museum. The results of this study indicate that: (1) Ethnomatematics is a scientific discipline that combines mathematics with culture. Which is where ethnomathematics can be a model of a mathematical approach in a cultural perspective which has very good potential for teachers to develop mathematics learning into contextual learning which can also introduce national culture to students. (2) There are 20 (twenty) objects that have the concept of second-dimensional and third-dimensional geometry. 13 (thirteen) artifact objects having a two-dimensional geometric concept, and 8 (eight) artifact objects having a three-dimensional geometric concept. (3) Small artefacts such as fossils, metal inscriptions, nekara and other similar small sizes are placed in a box-shaped glass protective case with a total surface area of 2.45 m2 consisting of a windshield covering an area of 1.4 m2 and top glass protector covering an area of 1.75 m2.