The Sikh Empire - Places & Architecture
With the establishment of the Sikh Empire, the political capital of the empire became the ancient city of Lahore. The spiritual capital of the empire became Amritsar with its central focal point of the historic Darbar Sahib at its heart.
Images of Darbar Sahib from this era reveal a plain or patterned Nishan Sahib with a light outer border.
Miri-Piri Nishan Sahibs
The Miri-Piri Nishan Sahib banners that stand in front of the Akal Takht today have a unique history. According to Sikh tradition two Nishan Sahib banners were said to have been first placed in front of the Akal Takht in 1606 by Guru Hargobind. These would have been destroyed during the raids of Ahmed Shah Abdali. In rebuilding the Darbar Sahib complex following Ahmed Shah Abdalis destruction of the complex, a Mahant of the Brahm Buta Akhara first raised the Nishan Sahib in front of the Akal Takht in 1770. 
This Nishan Sahib erected by Udasi Pritam Das broke down in 1823. It was replaced with a new Nishan Sahib with a iron base and gold plates erected by Desa Singh Majithia.  Desa Singh Majitia was an influential Sikh chieftain that had been appointed to manage Darbar Sahib by Maharaja Ranjit Singh during this time period.  This new Nishan Sahib fell down during a storm in 1841 whereupon his son Lehna Singh Majithia raised another golden standard in its place. Maharaja Sher Singh on his enthronement in 1841 placed another flag by its side, with more costly gold plates on it and endowed it with a Jagir (land grant) worth Rs 1,000 per annum. 
During a visit to Darbar Sahib the Austrian explorer and botanist Baron Charles Hugel who travelled throughout Punjab and Kashmir between 1831 and 1836  made note of the unique Miri Piri Nishan Sahibs that he saw flying at Darbar Sahib:
Before the entrance to the bridge are two large banners of red; on one is written, “Wah! Guruji-ke faith!” in white letters; and on the other, the name of Ram Das. These banners are from thirty to forty ells long, and are streached on masts and confined with iron chains. 
1. Sodhi Hazara Singh, A History & Guide to the Golden Temple, Amritsar, 1938, pg. 75
2. ibid, pg. 131
4. Sodhi Hazara Singh, A History & Guide to the Golden Temple, Amritsar, 1938, pg. 132
6. Baron Charles Hugel, translated from German with Notes by Major T.B. Jervis, Travels in Kashmir and the Panjab, 1845, pg. 394