Yet all that seems puny in comparison to the two-mile “Great Wall” that can seal off the channel from Lake Borgne to the east, or the billion-dollar west closure complex, which features the biggest pumping station on the planet.

Now, hurricane season has returned, as it does each June. Whatever storms might approach New Orleans this year or in the future, they will encounter a vastly upgraded ring of protection. The question is whether it will be enough.

When Katrina hit New Orleans in 2005, the city’s hurricane protection system became a symbol of America’s haphazard approach to critical infrastructure. The patchwork of walls and levees built over the course of 40 years was still far from complete when the storm came, and even the Army Corps of Engineers admitted that this was “a system in name only.” Flood walls collapsed, and earthen levees built from sandy, dredged soils melted away.

What has emerged since could come to symbolize the opposite: a vast civil works project that gives every appearance of strength and permanence. No other American city has anything like it. “This is the best system the greater New Orleans area has ever had,” said Col. Edward R. Fleming, the commander of the New Orleans district of the corps.

Marc Walraven, a district head in the Dutch ministry of transport, public works and water management, recently toured the defenses. While 100 percent safety is impossible, he said, and challenges in operations and maintenance can be expected as the corps passes the facilities over to local management in the coming year, “the constructions that have been built are in my opinion adequate to defend New Orleans.”