Question

The skyscraper that was built last year do you underline subject of this and it is an adverbial phrase a noun phrase a propositional phrase or verb phrase

Answer 1

The Answer?

Noun Phrase.

Here's Why!

Then subject, "The skyscraper that was built last year", is subject is post-modified by a restrictive relative clause which is "that was built last year". But still, the subject is a noun phrase.