What is the place of worship? What are the major features of this place?

As all Muslims do, Shia's pray in Mosques. The Imam Hussein Shrine in Karbala, Iraq is a holy site for Shia muslims.

-It is one of the oldest mosques in the world.

-It stands on the site of the grave of Husayn ibn ‘Alī, the second grandson of Muhammad, near the place where he was killed during the Battle of Karbalā in 680 C.E.

-The grave of Husayn is enclosed within a cage-like structure, found directly beneath the golden dome. Al Abbas Mosque is located nearby.

-The boundary wall of the shrine surrounds wooden gates covered with glass decorations. The gates open into a courtyard separated into smaller rooms or precincts with many "Iwans" along the walls.