For me it's a combination of extraordinary achievements in scientific fields, a very distinctive art aesthetic and the promotion of an ascetic life. Even the well connected aristocracy lived plainly by western standards. I'm inspired by the ideal of success through sheer determination and ingenuity, against all odds.

Having known folks who lived in the USSR and modern Russia, I recognize the romantic elements are the effect of powerful propaganda. In reality, people were burdened by not being able to meet basic needs and were afraid of their government. Engineering was done under the barrel of a gun.

Romantic elements aside, I think we can all recognize the USSR was responsible for remarkable accomplishments, ranging from sublime to deeply horrifying.