Daśāśvamedha Ghāṭa is one of the five supreme tīrthas (the Pañcatīrthī) of Kāśī. It lies on the bank of the Gaṅgā, between the Asī-Gaṅgā confluence to the south and Pādodaka Tīrtha to the north.

The name means “ten Aśvamedha”. It comes from the ten Aśvamedha (horse) yajñas that the righteous king Dīvodāsa performed here. Brahmā came to Kāśī in disguise and urged him to do this, so that Dīvodāsa would leave the city. The Liṅga that Brahmā installed here is Brahmeśvara, also called Daśāśvamedhīśvara.

Origin of the name

Before it had its present name, this tīrtha on the bank of the Gaṅgā was known as Rudrasaras, the lake of Rudra. It rose to supreme rank through the ten Aśvamedha yajñas (Daśāśvamedha) that Dīvodāsa performed here when Brahmā, in disguise, prompted him.

The puṇya (merit) of ten great Aśvamedhas made this stretch of the Gaṅgā one of the holiest ghāṭas in the universe. The Kāśī Khaṇḍa says plainly that all the tīrthas of the three worlds come to Daśāśvamedha to be purified, because Kāśī is the purifier of all.

Brahmā’s permanent home

Brahmā came to Kāśī in disguise and guided Dīvodāsa toward the ten yajñas. Then the holiness of the place overwhelmed Brahmā himself. Like the Yoginīs, Bhagavān Sūrya and the divine gaṇas before him, Brahmā chose to stay in Kāśī for good.

He installed a Liṅga at the site. It is called Brahmeśvara (Īśvara of Brahmā) or Daśāśvamedhīśvara (Īśvara of the Daśāśvamedha). Brahmā settled here as the guardian of this tīrtha.

Place in the Pañcatīrthī

The Pañcatīrthī is the group of five supreme tīrthas of Kāśī:

Asī confluence
Daśāśvamedha
Pādodaka (near Ādikeśava)
Pañcanada
Maṇikarṇikā

Together they form a sacred circuit. Walking around it and bathing in it gives liberation from rebirth. The Kāśī Khaṇḍa says: “By bathing in Pañcatīrthī a man ceases to take up the body consisting of five elements, or he becomes Pañcāsya, the five-faced Viśveśvara himself.”

Rewards of bathing here

One bath at Daśāśvamedha equals the puṇya (merit) of performing an Aśvamedha yajña.
Bathing here in the bright fortnight of Jyeshṭha, above all on Daśaharā (the tenth day), brings supreme puṇya.
During the bright fortnight of Jyeshṭha, all the tīrthas of the three worlds flow to Daśāśvamedha to bathe in this tīrtha.
Pūjā to the Brahmeśvara (Daśāśvamedhīśvara) Liṅga here destroys all the pāpa (sin) a person has gathered.

Sources

Skanda Mahā Purāṇa, Kāśī Khaṇḍa, Chapter 52
Skanda Mahā Purāṇa, Kāśī Khaṇḍa, Chapter 83