I practiced Aikido for a long time, in different places. My home dojo was in Ravenna, Italy, but I attended classes in Auckland, New Zealand, in Modena, Parma, Bergamo, and finally here in Vienna, Austria.
The green mat, named Tatami, is a must have in the Aikido practice, because of the frequent fall that the art requires. It’s also the major struggle for the casual Aikido teams because you can go running with just shorts and shoes but you can’t practice Aikido without a fairly large soft survace to land on.
The reputation of a dojo resides on the quality of their tatami. Most of the time is made of pre-cut squares of hard foam, shaped as jigsaw so to interlock with each other and stay in place. Bigger dojos have a custom made tatami that covers the entire area of practice without seams.
At the end of every class, traditional dojos require the students to swipe the tatami for the next class. The last class of the day cleans the entire dojo before leaving.
This practice gives everybody a sense of belonging. You are not just a student that pays the tuition, shows up, and attend the classes. Taking part of the maintenance of the dojo makes you feel part of the system. You contribution is important for the others and keeps things together.