SB 8.20.23

rasām acaṣṭāṅghri-tale ’tha pādayor
 mahīṁ mahīdhrān puruṣasya jaṅghayoḥ
patattriṇo jānuni viśva-mūrter
 ūrvor gaṇaṁ mārutam indrasenaḥ
Synonyms: 
rasām — the lower planetary system; acaṣṭa — observed; aṅghri-tale — beneath the feet, or on the sole; atha — thereafter; pādayoḥ — on the feet; mahīm — the surface of the land; mahīdhrān — the mountains; puruṣasya — of the giant Personality of Godhead; jaṅghayoḥ — on the calves; patattriṇaḥ — the flying living entities; jānuni — on the knees; viśva-mūrteḥ — of the form of the gigantic Lord; ūrvoḥ — on the thighs; gaṇam mārutam — varieties of air; indra-senaḥ — Bali Mahārāja, who had obtained the soldiers of King Indra and who was situated in the post of Indra.
Translation: 
Thereafter, Bali Mahārāja, who was occupying the seat of King Indra, could see the lower planetary systems, such as Rasātala, on the soles of the feet of the Lord’s universal form. He saw on the Lord’s feet the surface of the globe, on the surface of His calves all the mountains, on His knees the various birds, and on His thighs the varieties of air.
Purport: 

The universal situation is described herein in regard to the complete constitution of the Lord’s gigantic universal form. The study of this universal form begins from the sole. Above the soles are the feet, above the feet are the calves, above the calves are the knees, and above the knees are the thighs. Thus the parts of the universal body, one after another, are described herein. The knees are the place of birds, and above that are varieties of air. The birds can fly over the mountains, and above the birds are varieties of air.