Canto 1 - Boyhood
Bāla-kāṇḍa
Chapter 14: The Aśvamedha Sacrifice
Text 1.14.24

कारिताः सर्व एवैते शास्त्रज्ञैर्यज्ञकोविदैः।
शोभार्थं तस्य यज्ञस्य काञ्चनालङ्कृताभवन्॥

kāritāḥ sarva evaite śāstra-jñair yajña-kovidaiḥ
śobhārthaṁ
tasya yajñasya kāñcanālaṅkṛtā bhavan

kāritāḥ = sacrificial pillars were constructed; sarve eva = all; ete = these; śāstrajñaiḥ = by those who knew the scriptures that describe sacrifices; yajña-kovidaiḥ = and who were expert in practically carrying them out; śobhā-artham = for beautifying; tasya = the; yajñasya = sacrificial arena; kāñcana-alaṅkṛtāḥ = decorated with golden strips; bhavan = they were.

All these sacrificial pillars were constructed by those who knew the scriptures that describe sacrifices and who were expert in practically carrying them out. They were decorated with golden strips for beautifying the sacrificial arena.

This describes the construction of the pillars.