ISLA will be an astronomical observatory, operating at the upper limit of our planet Earth atmosphere, offering space like observing conditions in most aspects. ISLA can be maintained easily, modified if required, and operated for very extended periods without polluting the stratosphere. ISLA's two 4-m and four 2-m telescopes will operate diffraction limited from 0.3 micrometer, over the infrared, far-infrared to the sub-mm spectral range. ISLA's individual telescopes will permit imaging with 20 milli-arcsec spatial resolution in the optical. ISLA's telescopes can be combined to form an interferometer with a maximum baseline of 200 m with nearly complete coverage of the u, v plane. Interferometric resolution will be of the order of 20 micro-arcsec for the optical. ISLA will thus offer significantly better spatial resolution than the intercontinental VLBI radio interferometers. ISLA's efficiency will be many orders of magnitude better than comparable ground-based telescopes. The light collecting power of ISLA's interferometric telescopes are orders of magnitudes greater than the space interferometers under discussion. ISLA, being an aviation project and not a space project, can be realized in the typical time scale for the development of aircraft: about 5 years. ISLA's cost for the whole observatory, including its movable ground station, etc., will be of the order of a typical medium size space mission. ISLA's lifetime will be in excess of many decades, as it can easily be maintained, modernized, repaired and improved. ISLA will become the origin of a new astronomical international organization with many participating countries in Europe, etc. ISLA's telescopes will be of the greatest importance to all astronomical fields, as it will permit to study much fainter, much more distant objects with microscopic spatial resolution in wavelength regions inaccessible from ground. ISLA's many telescopes permit easily simultaneous observations at many wavelengths for rapidly varying objects, from symbiotic stars to QSOs.