ARIES hosts three telescopes of apertures 1.04m, 1.3m and 3.6m and an upcoming 4m Liquid Mirror Telescope. The 1.04m optical telescope, located at Manora Peak, near Nainital, is being used as a main observing facility by the ARIES scientists since 1972. Recent increase in light polution due to Nainital city, ARIES has now developed a new astronomical site at Devasthal after a comprehensive site surveys done in different places in the Himalayan region.

Devasthal ("Abode of God") is a mountain peak located at a distance of ~60 km from ARIES near Dhana-chuli, which has the advantages of having dark skies and excellent observing conditions.  Devasthal has a longitude of 79.7 E, latitude of 29.4 N, and an altitude of ~2450 m above msl. The site is away from major urban settlements in the region. Its line-of-sight distance from the Manora Peak at Nainital is nearly 22 km. This site was chosen after an extensive site characterization conducted during 1980 - 2001 in the central Himalayan range. The main advantages of Devasthal site are in its dark skies, sub-arcsec seeing, low extinction and at the same time being easily assessable and manageable.

The site development at Devasthal was started after ARIES moved to DST in 2004. In total,  41,692 square meter of land has been transferred to ARIES from Uttrakhand Goverment which includes roads, base camp area and  telescope site.  The observatory site now hosted different telescopes. Their detail are given below: