From the vantage point one can see the Grumari Beach and the Atlantic Forest reserve.

The observatory is imbedded in the midst of one of the last natural reserves of Atlantic Forest in the city. To reach, cross all the beach Grumari (for those coming from the Bar direction) follow the left, up the hills leading to the Pedra de Guaratiba. The structure is lower, compared to the Prainha, with eight parking spaces and a parapet fan-shaped. From the top, one can see the coast.

Source: "http://rioshow.oglobo.globo.com/passeios/atracoes-turisticas/mirante-de-grumari-3004.aspx"