Trump, accompanied by his wife, daughter Ivanka and son-in-law Jared Kushner, arrived here from Ahmedabad.
The Taj Mahal, which was built by Mughal Emperor Shah Jahan in memory of his wife Mumtaz Mahal who died in 1631, has been refurbished for the visit.
President Trump and the First Lady held hands as they strolled at the Taj complex and later wrote in the visitors' book. They were also briefed about the history and importance of the monument
The US President's visit to Agra and Taj has generated huge excitement among local residents. Some shops have even displayed their own banners, welcoming Trump to India.
Trump also took to Twitter to express his sentiments about his first official visit to India, which began with a visit to Ahmedabad.
"First lady and I have travelled 8,000 miles around the world to give a message to each citizen of this country – America loves India, America respects India, and the people of America will always be true and committed friends of the people of India," the American leader tweeted in Hindi.
From the Kheria airbase here, Trump's convoy of over 30 vehicles drove to Oberoi Amarvilas hotel near the Taj Mahal complex, as over 15,000 school students who lined up both sides of the route held US and India flags and cheered the US president as his motorcade passed by.
Massive billboards bearing greeting messages and pictures of Trump, First Lady and Modi dotted the nearly 13-km convoy route as street roundabouts decked up with US and India flags symbolised the US-India friendship.
An extensive three-layered security is in place for his Agra visit, and authorities had got the Taj Mahal premises cleared of visitors by noon, hours ahead of Trump’s visit to the celebrated architectural landmark.
Watch: Donald & Melania Trump visit Taj Mahal, pose for cameras holding hands
Trump and the First Lady enjoyed the view of the marble marvel in the evening as a cool breeze added to the pleasant weather.
They also posed for pictures for photographers. The couple will spend about an hour at Taj to catch the sunset from the UNESCO heritage site, before heading to Delhi.
The last US president to visit the the Mughal-era wonder was Bill Clinton who had come to India in 2000. He had seen the Taj along with daughter Chelsea Clinton.
In 1959, then US president David Dwight Eisenhower had visited Taj along with then prime minister Jawaharlal Nehru.
From massive billboards bearing greeting messages to street roundabouts decked up with US and India flags, Agra had waited excitedly to welcome President Trump and authorities made arrangements to present a "lively Agra" to the visiting President, seeking to shake off the old tag of ‘city of ghosts’.
"During Clinton’s visit the city streets were deserted due to security arrangements, prompting him to call it a ‘city of ghosts’. This time the excitement can be felt in the air," said Mohit Kumar, who works at a hotel in Tajganj area.
"I was very young in 2000 when Clinton visited. We are very excited and happy that another US President has come to our city due to which the civic amenities have been improved," he said.
Trump arrived in Agra after jointly attending with Prime Minister Narendra Modi the mega ‘Namaste Trump’ event at the newly built Motera cricket stadium in Ahmedabad.
On his arrival at the airbase, over 250 artistes drawn from different parts of Uttar Pradesh performed ‘Mayur dance’, ‘Rai folk dance’, Dhobia folk dance’ as sonorous sounds of 'bumrasia' nagada, dholak, mridang, added to the festive ambience.
A giant billboard there featuring Trump, First Lady Melania Trump and Prime Minister Modi greeted the couple with a message – ‘Grand welcome of India’s best friend to the City of Love –Agra'.
Trump was received at the Kheria airbase by Uttar Pradesh Governor Anandiben Patel and Chief Minister Yogi Adityanath.
"From the airport, the US President’s convoy travelled till the Oberoi Amarvilas hotel situated near the East Gate of the Taj Mahal complex. From there the President and his family and members of high-level delegation accompanying him moved into eco-friendly golf carts to travel into the monument premises," a senior official said.
As per Supreme Court directions, petrol or diesel-operated vehicles are not permitted within 500 m of the Taj Mahal’s gate.
The architectural marvel inscribed into the UNESCO World Heritage Site in 1983 is made of white Makrana marble and red sandstones, and renowned for its intricate inlay work on the stone surface.
Taj Mahal, considered one of the seven wonders of the world, stands on the bank of Yamuna, and is always high on the itinerary of visiting heads of state.
In 2015, the then US President Barack Obama was scheduled to visit the monument during his India visit. It is said he could not do so due to security reasons.
It is one of the most photographed sites in the world.