In this paper we present the application of microgravity, magnetometry, and electrical resistivity tomography (ERT) methods to an archaeological investigation.The aim of this study was to obtain information about the subsurface and associated buried structures beneath the Late Byzantine 'Lion Church' , inthe ancient town of Umm er-Rasas.In order to test this sitea numberofgravityandmagnetic stations were carried out on the mosaic floor of the church. Gravity data were collected on a 1-m grid station along survey lines spaced 1m apart. Magnetic data were taken at heights of 0.8 m and 1.3 m, at about10-cm intervals along the same traverses used in the gravity survey in order to obtain a direct comparison between the two methods. Resistivity measurements were carried out utilizing the Wenner array with 2-m electrode spacing along profiles spaced 2 m apart close to the church wall in order to investigate water leakage below the church floor. Both microgravity and magnetometry methods found a number of structures with contrasting physical properties to those of the surrounding material. The archaeological interpretation of such structures is in terms of two possible floors of a building with remains of walls, rooms, paths and foundations. Resistivity data based on two-dimensional-modelling show a highly conductive region close to the church wall. This is may be attributed to rain water which seeps under the mosaic floor of the church.