Unfortunately they would not let me take any photos of this fresco masterpiece. In fact, I heard different things about when the chapel was open, so I posted the official sign outside the chapel (which is in both Spanish and English).
There are pictures online, such as this view of the whole chapel:
Diego Rivera painted several images of Tina Modotti in this chapel fresco:
In 1926 Diego Rivera's wife Lupe Marín asserted that her separation from her husband was caused by his affair with Modotti, a byproduct of Modotti's nude modeling for him for the murals as "the Abundant Earth" at the National Agricultural School in Chapingo, near Texcoco [1926-27]. Their affair lasted for about a year and he painted her five times in the Chapingo murals, including as "The Earth Enslaved", "Germination", and "Virgin Earth"
The Rivera chapel occupies
only part of the main building on campus
We also went to see the fresco mural in central part of Mexico City --Dream of a Sunday Afternoon in the Alameda Central -- by Diego Rivera. I went with Francisco Delgado, who did a fresco with me in 2011, and was about to do a relief print edition in Oaxaca.