Final answer:
Guru Hargobind Ji erected the Akal Takht fortification in Amritsar, a site of both spiritual and temporal authority within Sikhism.
Step-by-step explanation:
The fortification that Guru Hargobind Ji put up in Amritsar is known as the Akal Takht. The Akal Takht is a significant religious and historical edifice within Sikhism, and its establishment is one of many events that underscore the faith's rich history and heritage, especially in the context of its interactions with Mughal rulers. Notably, the Akal Takht was established by Guru Hargobind as a place of justice and consideration of temporal issues, signifying the dual spiritual and worldly authority that the Guru held. Guru Hargobind Ji erected the Akal Takht fortification in Amritsar, a site of both spiritual and temporal authority within Sikhism.