General sources like dictionaries, handbooks, encyclopedias are great to start with. They provide background information and help get you thinking about a topic. Use the Advanced Search in the library catalog, and look Spain (in Subject) AND Encyclopedia (in Subject) AND Culture (in All Fields). Try various combinations.
You can also check the encyclopedias tab of our Reference Shelf research guide.
Once you explored a topic, use the tool on the right to help you generate as many terms as possible specific to your topic.
This list should get you started:
Encyclopedia of Contemporary Spanish Culture by 
Historical Dictionary of Spain by 
Medieval Iberia by Credo Reference is an online source of encyclopedias, dictionaries, and much more. It is a great place to explore topics.
Use this tool to help you brain storm for search words, then use "Advance Search" features in library catalogs or databases to combine these terms.
Please feel free to post your own suggestions, or use it to organize the words in sub-topics by shuffling words around!
Consult General Tips for Finding Resources in Different Languages on the Modern Languages guide home page.