We made a cylindrical hole in a Si (110) wafer, and curried out first in-situ observations of the inner surfaces of it to study various high index surfaces and vicinal surfaces simultaneously in the UHV condition by REM-RHEED method. Our studies revealed seventeen surfaces to show well-defined RHEED patterns in the [110] zone. So-called hill and valley structures were formed on six regions. We attempted to observe the equilibrium shape of the Si vicinal surfaces. Step properties of the (111) and the (110) surfaces were estimated from the analysis of the equilibrium shapes of the vicinal surfaces. Also we determined the roughening phase transition temperatures on the various high index surfaces.