It doesn't seem like 40 million Euros would do much to restore marble buildings that are two thousand years old.
This wouldn’t have happened if it hadn’t been so well made. The Circus Maximus was rebuilt of more durable materials after the wood predecessor burned to the ground, but the Colosseum is made of stacked barrel vaults which converge, thus leaning on each other. This also makes the movement in and out of the crowd easy to handle. If memory serves, one of the great columns used to mark the end of the straightaways survives at the site of the Circus Maximus, and not a lot else, considering its sheer size.
40 million Euros.....
Probably for 2 bathrooms and an information booth.