On the summit of Mount Sumeru is Brahmapurī, the residence of Lord Brahmā. Each of its four sides is 10,000 yojanas long. Surrounding Brahmapurī are the cities of King Indra and seven other demigods. These cities are one fourth the size of Brahmapurī.
(Srimad Bhagavatam------5:16------summary).

Surrounding Brahmapurī in all directions are the residences of the eight principal governors of the planetary systems, beginning with King Indra. These abodes are similar to Brahmapurī but are one fourth the size.
(Srimad Bhagavatam------5:16:29------translation).

Brahmā's township is known as Manovatī, and those of his assistants such as Indra and Agni are known as Amarāvatī, Tejovatī, Saṁyamanī, Kṛṣṇāṅganā, Śraddhāvatī, Gandhavatī, Mahodayā and Yaśovatī. Brahmapurī is situated in the middle, and the other eight purīs surround it in all directions.
(Srimad Bhagavatam------5:16:29------purport).

The Ganges River, emanating from the lotus feet of the Lord, inundates the heavenly planets, especially the moon, and then flows through Brahmapurī atop Mount Meru.
(Srimad Bhagavatam------5:17------summary).

The branch of the Ganges known as the Sītā flows through Brahmapurī atop Mount Meru, and from there it runs down to the nearby peaks of the Kesarācala Mountains, which stand almost as high as Mount Meru itself.
(Srimad Bhagavatam------5:17:6------translation).

Similarly, the branch of the Ganges known as Alakanandā flows from the southern side of Brahmapurī (Brahma-sadana). Passing over the tops of mountains in various lands, it falls down with fierce force upon the peaks of the mountains Hemakūṭa and Himakūṭa. After inundating the tops of those mountains, the Ganges falls down onto the tract of land known as Bhārata-varṣa, which she also inundates. Then the Ganges flows into the ocean of salt water in the south.
(Srimad Bhagavatam------5:17:9------translation).