* The 20th century saw incredible technological advancements. (Describing a time period)
* This painting is from the early part of the last century. (Referring to a past century)
* Historians debate the defining characteristics of the current century. (Referring to the present century)
* She lived through nearly a whole century. (Referring to a person's lifespan)
* The building is a testament to the architectural styles of its century. (Referring to a building's age)
The best way to use "century" depends on the context of your sentence.