Ruins of the Library of Celsus at Ephesus
Wikipedia is a great starting place for your research; it often provides useful background information, lists important names and dates, and gives you ideas for further exploration. However, because the quality and reliability of research varies widely from article to article, Wikipedia is not an acceptable source to cite in scholarly research.
That said, most Wikipedia articles include linked references and further reading sections that may lead you to sources you can use and cite in your research.
If you have questions about whether a source is reliable, ask your instructor or a librarian.