Valmiki Ramayana Bala Kanda Sarga 5 Shloka 19
Original Shlokaविमानमिव सिद्धानां तपसाधिगतं दिवि । सुनिवेशितवेश्मान्तां नरोत्तमसमावृताम् ।।1.5.19।।
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दिवि in heaven, तपसा through austerities, अधिगतम् acquired, सिद्धानाम् by siddhas, विमानमिव like an aerialcar, सुनिवेशितवेश्मान्ताम् of perfectly constructed palaces, नरोत्तमसमावृताम् inhabited by noblest of men.
Like an aerial car acquired by the siddhas in heaven through their austerities, the palaces were perfectly constructed in rows and inhabited by the noblest of men.