The THz undulator beamline provides coherent femtosecond (fs) – picosecond (ps) THz pulses for pump-and-probe experiments with the fs XUV pulses from FLASH. First light has been delivered into the FLASH experimental hall 'Albert Einstein' in November 2007. The THz pulses are generated by a purpose built undulator implemented in series to the XUV undulators. The design of the beamline allows to overlap a XUV pulse and a THz pulse generated by the same electron bunch at the end of BL3. The pulses are naturally synchronized, down to few fs. The pulse energies lie within the microjoule regime.