Systems and methods to provide navigational guidance to reach a package located inside a building. Low-energy wireless transmitting devices (e.g., Bluetooth devices) are used to transmit their identifiers. Some of the devices are placed at known locations inside the building; and some of the devices are attached to packages. When a mobile device detects the identifier of a device placed at a known location and the identifier of a device attached to the package, the location of the package is identified and recorded based on the known location of the device. Navigational guidance is provided to a mobile device of a user to reach the package based on the recorded location of the package and/or the location of any of the devices the mobile device can detect within the communication range from the current location of the mobile device.