I went to Seattle last week for the first time.
Seattle was beautiful
Seattle is beauitful
At that moment it was beautiful. but the be verb is not an action verb i can't make it past tense
You can say "Seattle was beautiful" in this way. It relates to your past action, not to the present state of the place.
"I went to the beach last week. It was beautiful."
"I went to London last week. It was busy."