What type of sentence is the sentence below?:

West of downtown, Memorial Park is a 14-acre green space that is the oldest park in Indiana.

Complex.

Explanation:

Compound sentence is a type of sentence that has to have at least two independent clauses (have subject and a verb and together they give us a complete thought) which are united with a comma, conjunction or a semicolon.

Complex sentence is a type of sentence that consists of one independent clause and one or more dependent clauses (can not stand alone).

Simple sentence usually consists of just one independent clause (can stand alone).

Compound-complex sentence is a type of a sentence that consists of at least two independent clauses and at least one dependent clause.

So in the given sentence we have one independent clause and one dependent which makes it a complex sentence.