Ngalau (Cave) Datuk Marajo Ali is located at Jorong Koto Nan Gadang, Kenagarian (State) of Pilubang, Harau District, Lima Puluh Kota Regency. Ngalau Datuk Marajo Ali is facing southwest (2100) with an opening of 10 m wide. The depth of its front space is 9.5 m, while behind it is a passage 10 m long with a sloping front slope. The ngalau has wide enough room with low cave roof at the back. The problems are: how are the relations between artifacts, space utility, and the forms of activities that took place at Ngalau Datuk Marajo Ali? How are they compared to the artifacts found at other cave around Harau Valley? The method employed during data collection phase was explorative using inductive reasoning, while the writing method was qualitative-descriptive. In general Ngalau Datuk Marajo Ali has wide enough space without stalactite or stalagmite, and is divided into southwest and northeast sections. The southwest section has lower surface than the northeast section. The rock surface of the northeast section is relatively flat so that it was comfortable to sit or stand there, except in the innermost part. Results of the excavation show that the activities in the southwest section were varied, based on the artifacts, artifactual context, and stratigraphy. It shows that the cave was used several times for different purposes. It is assumed that the activities were related to the Paderi War (1821 – 1838) as a hiding place, a hiding place during Indonesian independence war (before 1945), and gambir processing activities (gambir kitchen) in around 1945s