A system utilizes radio frequency identification (RFID) technology to determine the precise location of assets within a large area or building. RFID tags are attached to the assets. A mobile RFID portal, which includes an RFID tag reader, is moved along a select path through the large area or building to read information from RFID tags present in the vicinity of the path. The mobile RFID portal may be moved along the floor or on an overhead rail. The RFID tag information is analyzed along with data on the positions of the mobile RFID portal along the path and/or data on the times-of-read to determine the location of assets associated with the read RFID tags.