Trapped Underground

I had a dream.

In it, I take the Keio line and get off at a station in Suginami-ku.

There is a huge cube made of brown rocks, which look like an ancient ruin, in front of the station.

I'm a member of the investigation team that researches the cube.

We find an entrance behind the cube. This entrance is so narrow that a parson can only fit through it sideway.
We go through the narrow passage and come into a square. There are stairways on the other side.

There's a spiral staircase. The members of our team go down in a line.

After we have been going down for some time, we come to a wide space. There is nothing left now, but we talk about how there used to be a body of an aristocrat.

We research there, and are come back up to ground level. I’m ordered to be at the top of our team, although I don’t know the reason.

I go up the stairways until I realize that the stairway is getting smaller. After a while my head won’t fit through.

Finally I stop and the members of our team are in a line behind me. I wonder what I should do.

Postscript:
Most of my dreams end with the situation that I’m confused and don’t know what to do.