Can an article change the meaning?

European architecture has a graceful and exquisite style.

This means that European architecture in general has the stated qualities. You can provide many examples, although there can be exceptions. You may or may not be comparing European architecture to a different type of architecture.

The European architecture has a graceful and exquisite style.

Here, the European architecture is a definite noun phrase and you will say this when you assume that the person or people you are talking to (that is, your "audience") knows or can identify which European architecture you're talking about. A common context would be the European architecture that you've just mentioned. And the use of this definite noun phrase the European architecture is almost assuredly going to be used in comparison or by contrast to some other type of architecture.

European architecture has a graceful and exquisite style could be used when talking about European architecture at large. The European architecture has a graceful and exquisite style could be used when talking about a specific piece of architecture, where "The European architecture" is being used to describe some attributes of that particular piece of architecture.