In the article entitled, The Altar of Pity in the Athenian Agora, by Homer Thompson (Hesperia, vol. 21, no. 1, 1952, pp. 47-82) we read an excellent study on the altar of Pity in the Athenian Agora. Statius (Thebais. xii, ll. 481) talked about the altar and cult of Pity at the Athenian Agora:

Urbe fuit media nulli concessa potentum / Ara deum ; mitis posuit Clementia sedem

The altar of Pity in Athens has been consecrated by the children of Herakles or according to Apollodorus (ii, 8, 1) Herakles’ children took refuge at the altar.

Pausanias (i, 17, 1), claimed that there was no other altar of Pity in Greece except of the one in Athens. According to Αρχαιολογική Εφημερίς (1883, p.150 no, 43) there was another altar of Pity in by the temple of Asklepios in Epidauros which was consecrated after the time of Pausanias.