I toured a Concorde. Take a look inside the discontinued supersonic commercial jet flown by celebrities and royals.

• Concorde, the first and only supersonic commercial jetliner, operated from 1976 to 2003.

• Flown by royals, celebrities, and executives, it was discontinued because of high operating costs.

• A Concorde plane is open for public tours at the Intrepid Museum in New York City.

In 1962, the governments of Britain and France signed the Anglo-French Agreement, pooling their money and resources to develop a supersonic commercial jet. The name "Concorde" was chosen because it means unity or harmony in both English and French.

The first test flight was conducted in 1969, and Concorde flew commercially for the first time in 1976.

Concorde's ability to cross oceans at twice the speed of sound attracted high-profile passengers, including celebrities, business executives, and members of the royal family. But its high operating costs and a deadly crash led to its retirement in 2003.

Modern aviation startups are working to revive supersonic passenger air travel with new technology, but they also face challenges around economic viability and safety.

Since Concorde jets are no longer operational, the planes have become museum pieces, providing visitors with a taste of the luxurious flight experiences they once provided.

In May, I toured a Concorde jet at the Intrepid Museum in New York City. The sea, air, and space museum is housed on a 900-foot-long aircraft carrier. Take a look inside.

The last Concorde flight took off in 2003, and the Intrepid Museum added one of the jets to its collection that same year.

A total of 20 Concorde planes were built, and 14 flew commercially through British Airways and Air France, with most routes flying between New York City and London and New York City and Paris. Concorde's supersonic speed caused loud sonic booms upon breaking the sound barrier, which limited its routes to those above water.

Concordes were ultimately discontinued because of high operating costs and safety concerns. British Airways spent about ￡1 billion a year on its fleet of Concorde jets, which proved unsustainable, according to the Intrepid Museum.

In 2000, a Concorde flying from Paris to New York burst into flames and crashed shortly after takeoff when a blown tire ruptured the plane's fuel tanks, killing 113 people. All Concordes were grounded for a year and rebuilt with stronger fuel tanks, but the business never recovered, contributing to Concorde's retirement.

Concorde's record flight time from New York City to London was 2 hours, 52 minutes, and 59 seconds, making it a popular choice for frequent travelers.

Celebrity passengers included Queen Elizabeth II, Christie Brinkley, Phil Collins, Paul McCartney, and the British oil executive Fred Finn.

Touring Concorde's cabin at the Intrepid Museum requires a separate timed reservation.

Regular admission to the Intrepid Museum costs $36 per adult, and the Concorde tour costs an additional $11. Tickets can be purchased on the Intrepid Museum's website.

I didn't realize that Concorde tickets were sold with timed admission for tours every 30 minutes, so I missed my slot while exploring the USS Growler, the only nuclear-missile submarine in the US open to the public. I went to the box office and a manager was able to rebook me on the next Concorde tour.

Boarding the plane at the Intrepid Museum felt just like boarding a regular flight, except without the noise of a busy tarmac or jet engine.

Before boarding, Concorde passengers would relax in a special Concorde lounge with an open buffet.

The overhead bin space on the Concorde looked standard to me.

Concorde passengers would drop their luggage off in the Concorde lounge.

On the tour, I got to sit in Concorde class, which was a tier above first class.

At 204 feet long and with a fuselage that was 9 feet 5 inches wide, Concorde planes held up to 100 passengers, though full flights were rare. For comparison, a Boeing 737-700 measures just more than 110 feet long with a 12-foot-4-inch-wide fuselage and seats 149 passengers, according to Boeing.

In the late 1990s and early 2000s, tickets cost up to $12,000 round-trip, which would equal about $20,000 today when adjusted for inflation.

Queen Elizabeth always sat in seat 1A.

As the window seat in the first row, 1A was one of the most private seats on the plane.

My seat felt more like a comfortable armchair than a plane seat.

The seats used on the tour were covered in plastic to help preserve the luxurious leather.

Concorde's cruising speed was Mach 2, or about 1,350 mph.

Each of the Concorde's four engines featured 38,000 pounds of thrust and could take the plane from zero to 250 mph in under 30 seconds, our guide said.

The Concorde's windows were smaller than other aircraft to prevent them from cracking under the pressure of the plane's supersonic speed.

I was surprised by how small the windows were compared with the windows on commercial flights I'm used to.

Our tour guide passed around scans of Concorde artifacts such as a ticket from 1997.

Dolores Peterson paid $6,703.04 for an Air France Concorde flight from New York to Paris in 1997.

The guide also shared a refueling sheet from 1976 that showed how much fuel a Concorde plane used, contributing to its exorbitant costs.

"Upon takeoff, this plane weighs about 408,000 pounds. More than half of that, 209,000, is in fuel alone," our guide said. "It burns about 2 tons of fuel, about 1,800 kilos, just taxiing. It's an extremely thirsty bird."

After the short presentation concluded, we were free to wander the cabin.

Concorde's logo was displayed near the door of the plane.

A set of custom Concorde china dishes was on display — no plastic cutlery here.

Food was prepared by a gourmet chef. Seasonal menus included beef Wellington, venison, and quail with wine pairings chosen by a sommelier.

The lavatory looked like a standard airplane bathroom with a bit more space and a few extra amenities.

The bathroom was decorated with faux-marble finishes and extra toiletries.

For me, the highlight was peeking inside the flight deck once occupied by a captain, a first officer, and a flight engineer.

Before the terrorist attacks of September 11, 2001, Concorde passengers could mingle with the pilot and crew in the cockpit as part of the exclusive flight experience.

The flight engineer sat in the seat on the right in front of the large instrument panel.

The flight engineer was responsible for every system on the plane, including fuel management and landing gear, and had the most extensive training of any crew member.

"He's forgotten more about Concorde than most people will ever know," our tour guide said of flight engineers.

After my tour of the Concorde concluded, I climbed higher on the USS Intrepid to get a better view of the historic aircraft.

While many contemporary celebrities opt to fly on private jets, Concorde offered record-setting flights across the ocean at twice the speed of sound, seemingly making it worth their while.

Read the original article on Business Insider