The Duke and Duchess of Cambridge have heard first-hand about the horrors of the Mumbai attacks, at the start of a seven-day tour of India and Bhutan.
The couple talked to survivors and paid respects at the Taj Mahal Palace Hotel to those who died in the 2008 assault.
The royals later took part in a game of cricket with local children.
Day one of the visit ended with the duke and duchess attending a charity fundraising dinner with Bollywood and sporting stars.
Later in the tour they will also visit the Taj Mahal in Agra where in 1992 William's mother, Diana, Princess of Wales, was famously photographed sitting alone.
The gala night, to celebrate India's film industry, attracted Bollywood stars including King Khan, cricket legend Sachin Tendulkar and actress Aishwarya Rai Bachchan.
The duchess wore a sapphire blue Jenny Packham gown and matching blue earrings created by Indian jewellery designer Amrapali.
During a speech at the event Prince William said: "When Catherine and I were married, India was the first place on Catherine's list that she told me that she wanted to visit. Two children and five years later, we have finally made it - and we are both honoured to be here."
He said they were "on a journey to get to know the vibrant India of the 21st Century".
Earlier in the day the couple laid a wreath of white lilies at a memorial in the hotel commemorating those who died in 2008.
The duke and duchess, who are travelling without their children, later chatted with hotel staff, including chef Raghu Deora, 41, one of the survivors of the attack.
Kensington Palace said the duke and duchess had been informed on their arrival in Mumbai about the explosion and fire at a Hindu temple in Kerala, and sent their thoughts to all who were assisting the victims.
By BBC royal correspondent Peter Hunt
After some unflattering media coverage, the couple that represent the future of the British monarchy will be hoping that this tour will generate more positive headlines.
Prince William, an air ambulance pilot, has been accused of being "work shy" and "throne idle".
His supporters insist he's the heir-but-one to the throne and he's balancing his flying career with his responsibilities as a senior royal and his desire not to be an absent father.
This visit to India and Bhutan will help to establish if the claim of "work shy" sticks - as "Air Miles Andy" has to his uncle - or whether it is replaced by a more favourable appraisal of what the future king is trying to do.
When he gets to Bhutan, the recently-criticised representative of the Windsor dynasty will meet the king and queen of a fledgling democracy where the monarchy is revered.
Their next engagement was to visit Mumbai's Oval Maidan public park where they joined children playing cricket and met charity representatives.
The couple were coached by former Indian cricketers Sachin Tendulkar and Dilip Vengsarkar.
Tendulkar later tweeted that he was "bowled over by their humility".
Moving on to New Delhi during the week, the couple will pay their respects to India's founding father Mahatma Gandhi at the location of his 1948 assassination.
Their visit will also see them tour the Kaziranga National Park, famous for its one-horned rhinoceroses, tigers and elephants.
In Bhutan, the duke and duchess will meet the king and queen of the remote Himalayan kingdom.
King Jigme Khesar Namgyel Wangchuck and Queen Jetsun Pema both studied in the UK, and have even been compared to the duke and duchess.