9/11: Then and now — 16 years later

Yahoo News photographer Gordon Donovan recently returned to the scenes of many memorable images taken in New York City on Sept. 11, 2001. Donovan photographed the same areas to show what has changed since the terrorist attacks 16 years ago.

New obstacles have arisen, requiring some adjustments in camera angles to align with the original images. This is the sixth time Donovan has revisited the New York skyline; each year presents new challenges as the New York City landscape changes. (Yahoo News)

See more news-related photo galleries and follow us on Yahoo News Photo Twitter and Tumblr.

9/11: Then and now – 16 years later

New obstacles have arisen, requiring some adjustments in camera angles to align with the original images. This is the sixth time Donovan has revisited the New York skyline; each year presents new challenges as the New York City landscape changes. (Gordon Donovan/Yahoo News – AP)

9/11: Then and now – 16 years later

The twin towers of the World Trade Center burn behind the Empire State Building, Sept. 11, 2001. (Photo: Marty Lederhandler/AP)

9/11: Then and now – 16 years later

One World Trade Center is seen towering above the landscape in lower Manhattan behind the Empire State Building, Sept. 1, 2017. (Photo: Gordon Donovan/Yahoo News)

9/11: Then and now – 16 years later

Pedestrians on the waterfront in Brooklyn look across the East River to the burning World Trade Center towers on Sept. 11, 2001. (Photo: Henny Ray Abrams/AFP/Getty Images)

9/11: Then and now – 16 years later

People take photographs of the New York City skyline from Pier 1 at the Brooklyn Bridge Park on Sept. 4, 2017. (Photo: Gordon Donovan/Yahoo News)

9/11: Then and now – 16 years later

Smoke spews from a tower of the World Trade Center Sept. 11, 2001, after two hijacked airplanes hit the twin towers in a terrorist attack on New York City. (Photo: Mario Tama/Getty Images)

9/11: Then and now – 16 years later

The original World Trade Center towers can no longer be seen from the Trinity Church Cemetery in lower Manhattan, Aug. 13, 2017. (Photo: Gordon Donovan/Yahoo News)

9/11: Then and now – 16 years later

People walk in the street in the area where the World Trade Center buildings collapsed Sept. 11, 2001, after two airplanes slammed into the twin towers. (Photo: Mario Tama/Getty Images)

9/11: Then and now – 16 years later

Construction on Fulton Street at Nassau Street continues as people take photos with One World Trade Center in the background, Aug. 12, 2017. (Photo: Gordon Donovan/Yahoo News)

9/11: Then and now – 16 years later

Women wearing dust masks flee across the Brooklyn Bridge from Manhattan to Brooklyn following the collapse of both World Trade Center towers, Sept. 11, 2001. (Photo: Mark Lennihan/AP)

9/11: Then and now – 16 years later

People head toward Brooklyn from Manhattan across the Brooklyn Bridge in New York City, on Sept. 5, 2017. (Photo: Gordon Donovan/Yahoo News)

9/11: Then and now – 16 years later

A piece of debris, possibly from one of the crashed airliners, lies on the corner of Murray Street in lower Manhattan near the World Trade Center site on Sept. 11, 2001. (Photo: Chris Kline/AP)

9/11: Then and now – 16 years later

The scaffolding has returned as renovations begin on the building where the engine landed on the corner of Church Street and Murray Street several blocks away from the World Trade Center site on Aug. 19, 2017. (Photo: Gordon Donovan/Yahoo News)

9/11: Then and now – 16 years later

Pedestrians in lower Manhattan watch smoke rise from the World Trade Center towers, Sept. 11, 2001, after an early morning terrorist attack on the New York landmark. (Photo: Amy Sancetta/AP)

9/11: Then and now – 16 years later

West Broadway near Duane Street in New York City does not have the same view on Sept. 4, 2017, that it had 16 years ago. (Photo: Gordon Donovan/Yahoo News)

9/11: Then and now – 16 years later

The south tower begins to collapse as smoke billows from both towers of the World Trade Center on Sept. 11, 2001, left; New York City’s ever-changing skyline as seen from across the East River in Brooklyn on Sept. 4, 2017. (Photos: Jim Collins/AP – Gordon Donovan/Yahoo News)

9/11: Then and now – 16 years later

People run from the collapse of World Trade Center on Fulton Street on Sept. 11, 2001. (Photo: Suzanne Plunkett/AP)

9/11: Then and now – 16 years later

Sixteen years after the collapse of the World Trade Center towers, construction is now complete on a modern subway hub on Fulton Street connecting to One World Trade Center, on Aug. 23, 2017. (Photo: Gordon Donovan/Yahoo News)

9/11: Then and now – 16 years later

Pedestrians on Beekman Street flee the area of the collapsed World Trade Center in lower Manhattan following a terrorist attack on the New York landmark, Sept. 11, 2001. (Photo: Amy Sancetta/AP)

9/11: Then and now – 16 years later

Pedestrians walk past a parking garage on Beekman Street in lower Manhattan, on Aug. 12, 2017. (Photo: Gordon Donovan/Yahoo News)

9/11: Then and now – 16 years later

Pedestrians on Park Row flee the area of the World Trade Center as the south tower collapses following the terrorist attack on Sept. 11, 2001, left; buildings have been demolished for residential housing now under construction on Park Row in New York City, Aug. 12, 2017. (Photos: Amy Sancetta/AP – Gordon Donovan/Yahoo News)

9/11: Then and now – 16 years later

People evacuate the area surrounding the World Trade Center after it was hit by two planes on Sept. 11, 2001. (Photo: Mario Tama/Getty Images)

9/11: Then and now – 16 years later

People walk through the courtyard just outside of Brookfield Place (originally known as the World Financial Center) in lower Manhattan on Aug. 13, 2017. (Photo: Gordon Donovan/Yahoo News)

9/11: Then and now – 16 years later

With the skeleton of the World Trade Center twin towers in the background, New York City firefighters work amid debris on Cortlandt Street after the terrorist attacks on Sept. 11, 2001. (Photo: Mark Lennihan/AP)

9/11: Then and now – 16 years later

People make their way down Cortlandt Street toward Church Street near the World Trade Center site on Aug. 12, 2017. (Photo: Gordon Donovan/Yahoo News)

9/11: Then and now – 16 years later

A destroyed subway station near Ground Zero on the evening of Sept. 12, 2001. (Photo: Mark Lennihan/AP)

9/11: Then and now – 16 years later

Traffic along Church Street passes the Cortlandt Street subway station on Aug. 12, 2017, across the street from 3 World Trade Center. (Photo: Gordon Donovan/Yahoo News)

9/11: Then and now – 16 years later

The remains of the World Trade Center stand amid the debris following the terrorist attack on the building in New York, Sept. 11, 2001. (Photo: Alexandre Fuchs/AP)

9/11: Then and now – 16 years later

The World Trade Center buildings and National September 11 Memorial & Museum are seen along West Street on Aug. 19, 2017. (Photo: Gordon Donovan/Yahoo News)

9/11: Then and now – 16 years later

Medical and emergency workers standing in front of the Millenium Hilton look toward where the World Trade Center towers used to be after the terrorist attack on the twin towers on Sept. 11, 2001, left; tourists stand outside the Millennium Hilton on Aug. 12, 2017. (Photos: Mark Lennihan/AP – Gordon Donovan/Yahoo News)

9/11: Then and now – 16 years later

People make their way amid debris near the World Trade Center in New York, Sept. 11, 2001. (Photo: Gulnara Samoilova/AP)

9/11: Then and now – 16 years later

Tourists make their way along Fulton Street next to St. Paul’s Chapel of Trinity Church on Aug. 16, 2017. (Photo: Gordon Donovan/Yahoo News)

9/11: Then and now – 16 years later

Ash covers gravestones at Trinity Church, Sept. 11, 2001, after the attacks on the nearby World Trade Center towers in New York. (Photo: John Labriola/AP)

9/11: Then and now – 16 years later

The courtyard and cemetary of the historic Trinity Church in New York City on Aug. 19, 2017. (Photo: Gordon Donovan/Yahoo News)

9/11: Then and now – 16 years later

The skelton of one of the twin towers is seen as emergency personal keep the area secure on Sept. 19, 2001. (Photo: Gordon Donovan/Yahoo News)

9/11: Then and now – 16 years later

Pedestrians walk across Broadway at the intersection of Cortlandt Street just down the street from the World Trade Center site on Aug. 12, 2017. (Photo: Gordon Donovan/Yahoo News)

9/11: Then and now – 16 years later

A firefighter walks amid rubble near the base of the destroyed World Trade Center in New York on Sept. 11, 2001. (Photo: Peter Morgan/Reuters)

9/11: Then and now – 16 years later

Construction continues on Vesey Street near the National September 11 Memorial & Museum on Aug. 19, 2017. (Photo: Gordon Donovan/Yahoo News)

9/11: Then and now – 16 years later

Rubble-buried cars and a destroyed building in the aftermath of the Sept. 11 attacks in 2001. (Photo: Shawn Baldwin/AP)

9/11: Then and now – 16 years later

The rubble-buried cars have been cleared, and the damage to buildings has been repaired as traffic heads north on West Street past Brookfield Place (originally known as the World Financial Center) on Aug. 20, 2017. (Photo: Gordon Donovan/Yahoo News)