The city of Hong Kong hosted celebrations on Tuesday, marking the People's Republic of China's 70th anniversary.

It was a special and momentous occasion for both our country and for the Hong Kong special administrative region, said acting Chief Executive Matthew Cheung Kin-chung.

He spoke at a reception to celebrate the 70th anniversary at the Hong Kong Convention and Exhibition Centre.

The country has been transformed into an open, progressive, prosperous and rejuvenated nation after it went through severe tests and challenges with indomitable spirit over the past seven decades, said Cheung.

Hong Kong, in the meantime, has used its strengths to serve the country's needs and benefited from its rapid development, said Cheung.

The rising living standards of people on the mainland and Hong Kong shows that the country and city share common development and prosperity, he said.

Cheung pledged that Hong Kong will continue to adhere to the principle of "one country, two systems" and the Basic Law, defend the rule of law and maintain public order, safeguard national sovereignty, security, and development interests, and seize the opportunity of developing a diversified economy.

Only through these efforts will Hong Kong continue to thrive in the future, he said.

A morning flag-raising ceremony was held at Golden Bauhinia Square.

The disciplined services and Government Flying Service performed a sea parade and fly-past when the national and regional flags were rising as all attendees stood for the national anthem.

People from all walks of life in Hong Kong took part in various activities to express their blessings and love for the motherland, with songs and flags the most popular signifiers.

Hundreds of students at the Hong Kong University of Science and Technology watched the military parade and mass parade held in Beijing on television live in a lecture hall.

They then organized a flash-mob style gathering on campus, singing patriot songs to express their pride.

The activity was a great encouragement to patriotic students in Hong Kong, a third-year Ph.D. student surnamed Zhang told China Daily.

Most of them have felt a little frustrated at the recent turmoil, he said.

The participants were thrilled to see the advanced development of their motherland, said Zhang.

When the national anthem rings out, all got up from their seats and sang along with their compatriots in Beijing. They also cheered and applauded as the mighty troops and weapons appeared on screen, Zhang said.

"The singing echoed around the campus and red flags fluttered. Such courage and unity are undoubtedly more precious in the special period," said organizers in a statement thanking participants.

Patriotic citizens brought national flags to multiple attractions in Hong Kong to celebrate National Day.

A group of Hong Kong people brought an eight-meter long Chinese national flag onto a ferry boat and displayed it to both sides of Victoria Harbor.

Another group held up flags up as they climbed two of the city's most famous mountains – Lion Rock and Victoria Peak.

About 2,000 taxis decorated with national flags launched a cruise from Tsing Yi. They toured around districts in Hong Kong, bringing a festive atmosphere to the city.