The FERMI@Elettra free electron laser (FEL) user facility is currently under construction at the Sincrotrone Trieste laboratory in Trieste (Italy). It is a based on a seeded scheme that will provide an almost perfect transform limited beam and fully spatial coherent. It will cover the wavelength range from 100 to about 3 nm and in a short future down to 1 nm (by using higher harmonics). It is expected to be fully operative in the late summer of 2010. In this presentation we will report the layout of the photon beam diagnostics section with the preliminary tests, the radiation transport system to the experimental area, and the experimental hall facilities. A particular emphasis will be given to the optical solution and constrains due to the need of preserving the wave front and to avoid damage on the different optical elements, including slits, mirrors, gratings and all the diagnostic facilities. One of the main problems will be the necessity of using very large grazing incidence angle (up to 45°) on multilayers and single coating mirrors. These elements are mandatory to perform the transient grating experiments and to realize the delay lines, where time delay up to 1 nsec are required. This issue poses a serious problem in terms of energy density delivered and adsorbed by the optics and great care must be taken into the choice of the proper multilayer materials. Some studies on the reflectivity of multilayers and Carbon coated mirrors will be reported as well as the diagnostic tools to monitor the quality of the optics in operative conditions.