Sri Guru Arjan Sahib got Sri Harimandir Sahib built in the midst of the sarovar (tank) at the lowest level. Unlike other temples where the devotees have to climb up to offer their obeisance, here the devotees have to step down to offer their homage. This unique temple of God has been built at the lowest level because it represents the humility of Guru Nanak. Humility Incarnate Guru Arjan selected the lowest level because this was to be the Eternal seat of the Prophet of Humility, Sri Guru Nanak Sahib (manifest Sri Guru Granth Sahib).
The Sikhs were anxious to raise the plinth of Sri Harimandir Sahib higher than all the surrounding buildings and had strongly pleaded with the Guru for doing so but wonderful were Divine outpourings of the Humility Personified Guru Arjan. Some extracts:
Garibi Gada Hamari, Khana Sagal Rein Chhari Is Aage Ko Na Tikai Vekari
Sri Guru Granth Sahib, 628
"Humility is my mace; becoming the dust of everybody's feet is my sword. No evil doer can dare withstand these weapons"
Dasan Das Raen Dasan Ki, Jan Ki Tehal Kamawo, Sarab Sookh Badyai Nanak, Jiwon Mukhon Bulawo
Sri Guru Granth Sahib, 529
"I have become dust of the feet of the slaves of His slaves and I serve His servants. Thus, I have achieved true joy and honour, I live by uttering His Holy Name"