The Braun Center for Submicron Research, at the Weizmann Institute of Science, was founded in order to study and develop submicron semiconductor structures working in the mesoscopic regime. The heart of this Center is the MBE laboratory with a task to develop and produce the purest and the most complex GaAs based semiconductors structures (GaAs, AlGaAs, and InGaAs). Nanostructure fabrication is provided by an electron beam writing system, Ebeam, capable of producing 15 nm wide features. A large lithographic laboratory enables patterning down to some 1 micrometer. The process is enhanced by UHV evaporators, UHV plasma etching and deposition tools, and a SEM, with 12 angstroms resolution, for verification. Low temperature measurements are done in dilution refrigerators, and He4 and He3 systems. An optical laboratory of continuous and pulsed light allows optical characterization.