Day 6 was the re-visitation of another of my childhood interest – flying and space machines.

We spent the morning at the Intrepid Sea, Air & Space Museum. Sadly, it was the day before the space shuttle Enterprise was due to arrive at the museum. I remember staring in awe at its pictures as a kid and making models of it for science projects. Sigh, even a glimpse of the real thing would have been good.

The museum is based on the honorable Aircraft Carrier Intrepid. Intrepid served in WWII, Cold War, Vietnam War, survived kamikaze and torpedo strikes and was later used to recover NASA capsules.

We first watch "The Story of Intrepid" a short film narrating the impressive chronicles of Intrepid.

We then toured the Combat Information Center (CIC) at the Gallery Deck which showcases the vessel’s navigation and communications equipment, which was top secret during its time.

Ascending to the Flight Deck, we were treated to the collection of fearsome aircrafts on display against the backdrop of the Manhattan skyline.

There was the A-12 Blackbird, a spy plane built for the CIA, which could fly at high altitudes (~90,000 ft) and high speeds (3 x speed of sound) to avoid enemy detection and pursuit.

At the Exploreum Hall, there was a replica of the Aurora 7 capsule which Intrepid helped to recover when it landed back on Earth.

A British Airways Concorde sits adjacent to the Intrepid, the distinctive pointed nose reminding us of the prowess of the now retired supersonic jetliner.

Our visit closed with having lunch at the Mess Deck, where the crew members used to have their meals.

After lunch, we embarked on another walking tour, this time in downtown Manhattan. We started off at the 9/11 Memorial Museum.

As we approached the World Trade Center site, the partially-constructed skyscrapers were a lingering reminder of the devastation that the site had experienced.

The soaring twin towers have caved into the Memorial pools, designed to signify the loss of life and the physical void left behind by the attacks.

Water cascade down the sides forming the largest manmade waterfalls in the United States; the crashing of the water drowns out the sounds of urbanisation, creating a sanctuary for contemplation.

The perimeter bronze parapet is inscribed with the names of the victims. An interesting detail is that the arrangement of the names is not random but generated by a software based on an algorithm to create "meaningful adjacencies," based on "relationship" details.

The Survivor Tree, a callery pear tree, stands tall today but was recovered from the rubble badly charred. It’s resilience and amazing revival has lead to it being regarded as a symbol of hope and rebirth.

After the WTC, we toured the many historic buildings in the civic and financial district.

Located just across the street, the St. Paul’s Chapel served as a resting place for rescue and relief workers during 9/11.

We strutted down Wall Street passing by The New York Stock Exchange and the bronze ‘fengshui’ icon – the charging bull.

The former United States Customs House now serves as the National Museum of the American Indian.

We walked pass the iconic Brooklyn Bridge, a suspension bridge with enormous support towers which connects New York and Brooklyn.

The bricked Fraunces Tavern was once a bustling restaurant, well known partly for the superior cooking skills of owner Samuel Fraunces, and also for the being the incubator for political discussions and organization.

During the war, Fraunces was captured by the British and forced to cook for the officers. As a cook, he overheard discussions of the officers and fed strategic information to General Washington’s army. He also helped feed the American soldiers held prisoner aboard ships in the New York harbor.

Fraunces served as the household steward and chef to President Washington and his family after his inauguration.

A statue of George Washington stands in front of Federal Hall, the venue of his inauguration as the first President of the United States.

Seemingly constructed from Lego bricks, the Federal Reserve Bank houses 7,000 tons of gold (~1/4 of the world’s gold supply), stored securely five stories underground in a vault closed with a 90-tonne steel door.

Walking through City Hall Park offered views of the gothic-styled Woolworth Building.

Dubbed the “Cathedral of Commerce”, the building is magnificent for its terra-cotta clad exterior and grand, vaulted lobby ceiling. Sadly, the lobby is no longer open to the public after 9/11.

At the center of the park is the Jacob Wrey Mould Fountain, an exquisite water feature cornered by bronze candelabra and the flickering gaslights.

Beekman Tower, also known as 8 Spruce Street and New York by Gehry is a skyscraper designed by architect Frank Gehry, the man behind the strata building in MIT.

The structure oozes of Gehry’s unconventional and unsymmetrical architectural styles. The 76-storey building houses an elementary school and even a hospital!