As geological conditions are very complex in the limestone area, it is very important to investigate topography of limestone and distribution of karst and fractured limestone for analyzing stability of the foundation before construction. The surveying work in a limestone site of Malaysia by means of ground penetrating radar (GPR) shows that the interpretation results are consistent with the results of drilling. It is thus concluded that geological information of the foundation can be obtained by means of GPR, and the results can be regard as important reference materials for design and construction.