From "Brill's New Pauly":
(Γῆρας; Gêras, Lat. Senectus). Personification of hated old age, often
depicted as a small, naked, wrinkly old man with a long, drooping
penis who is defeated by Hercules in a burlesque way 1. As a
creature of the night (Hes. Theog. 225), G. belongs to the creatures
of horror found at the entrance to the Underworld (Verg. Aen. 6,275;
Sen. Herc. f. 696), although he resides on Olympus (Aristoph. Av.
606). Sisyphus is brought back to the Underworld by G. (Eust. Od.
11,592). A sanctuary is attested only for the extremely pious
residents of Gades (Philostr. VA 5,4).
The last sentence is a bit vague (or badly translated from the German edition: Ein Heiligtum ist nur bei den äußerst frommen Bewohnern von Gades bezeugt), but what the author means is clearly that the only known temple of Geras was in Gades (now Cadiz in Spain). Hence: no such temple in Athens.