Q:

Sequence of tences

Should you say me which is correct?

Our teacher said the place where we were going to stay IS supposed to have beautiful paysages.
Our teacher said the place where we were going to stay WAS supposed to have beautiful paysages

A:

I'll note that by paysages you probably mean the French word, which is landscapes in English. I'm going to use that word instead.

"Our teacher said the place where we were going to stay is supposed to have beautiful landscapes."

This might be said after their reservation was cancelled. It still does have beautiful landscapes—but they aren't going to stay there anymore.

"Our teacher said the place where we were going to stay was supposed to have beautiful landscapes."

This might be said after there was a terrible fire. It did have beautiful landscapes—but it doesn't anymore.

Generally speaking, if it's a fact that it still does have beautiful [landscapes], then the present tense would be used; if it's no longer a fact (or never was a fact—perhaps the teacher was lying or mistaken), then the past tense would be used.
So, it's a matter of context. It depends on the current situation at the time the sentence is spoken.

