Soldiers Discover Underground Portal and Black Force

by Anonymous
(Ft. Lauderdale, Florida, USA)

I'm looking for a late '60s or early '70s movie with the following scenes:

-Men (I think soldiers) remove a large brick/stone from an old building, and a man gets sucked in head first.

-Black force has glowing red eyes and gets stronger the longer it is free after being released

-Huge underground cavern/portal is discovered, and the missing brick removed by the soldiers creates an opening

-Blue-ish and dark hues in its look, and the black force's eyes really stand out.

Thanks! G