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There are also shafts known as ' zenith tubes ' which illuminate subterranean rooms when the Sun passes overhead found at places like Monte Albán and Xochicalco .
 Monte Albán, Xochicalco
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 Monte Albán, Xochicalco