We present measurements of nearby vertical and horizontal electric fields from leaders and return strokes associated with lightning strikes to the 100-m-tall Gaisberg Tower in Austria obtained in 2007 and 2008. The fields were measured at a distance of about 20m from the tower's vertical axis. Simultaneously with the fields, return-stroke currents were also measured at the top of the tower. The measured data are used to test engineering and electromagnetic models for the return stroke. In general, the agreement between measured waveforms and model-predicted ones is satisfactory.