This is the house Imam Mahdi (PBUH) grew up in (until age 5 when his father Imam Hassan al-Askari was martyred).
This is where both his parents are buried and I suppose Imam Mahdi visits this location frequently. If you had access to your childhood house where both your parents were buried, what would you do?
(this particular pic is a shot of “Sardab” where it is deeper than the living area to keep the food longer as it is much cooler. Sardab was a part of the small house Imam Hassan and wife and only child lived in!! It may actually be close to the grave of Imam Hassan al-Askari and his wife Lady Narjes (peace be upon them))
Sayyed Ibn Tavoos says I have heard Imam Mahdi sitting and praying for his followers in that very location [while I had stopped going further down on the stairs].