In 2013 I visited the Nabi Karim area in Paharganj, Delhi.
There I found what seemed like a derelict mosque or sarai with an entrance gate a little far away. It was inhabited by some rag pickers.
I found the idea of a U-shaped mosque a bit odd but there were mehrabs inside, so perhaps it was a Sarai.
This was the are where the famous 14th c Qadam Sharif dargah is located and was once a busy and popular shrine during Sultanate and Mughal Era.

Can you imagine my delight when on my visit to this area in 2019, for research on Shahjahanabad The Living City of Old Delhi, I saw a wonderful sight. It had been repaired by Intach Delhi chapter and looked totally different.

At first I didn’t realise it was this same place but later found it was.

To my surprise I read it used to be an Imambara.
That’s as per the board there and there are references to an imambara which was converted into a hospital for infectious diseases in Paharganj by the British in Maulvi Zafar Hasan’s book.

I’m posting the 2013 &2019 photos.