It’s dark by the time I land in Hanoi and noticeably colder – in fact the temperature in Mr Minh’s car says it’s 15 degrees, so less than half as warm as when I left Siem Reap. Mr Minh, my driver, speaks no English but fortunately Sunny, my guide for the next two days, is fluent and – as his name suggests – a beacon of cheerfulness. He needs to be as the rain starts falling during our long drive from the airport to the city centre.

It’s past 9pm when I check into the lovely Hotel de l’Opera and, grateful that I was served a meal on the flight from Cambodia, I decide to forego dinner in the hotel in favour of a stroll around the neighbouring area to get my bearings. Before leaving I call Coman, who is sat in the BA lounge at Hong Kong airport waiting for his connecting flight. We’re already missing each other – it’s very strange to suddenly be apart after spending every minute together for the past month.

The rain has eased to a light drizzle by the time I head out, and it’s only a five minute walk to the centrepiece of Hanoi, Ho Hoan Kiem, the Lake of the Restored Sword. The whole area around it is pedestrianised at weekends and as I circumnavigate it, I pass groups of teenagers on the streets dancing, shooting videos, roller skating and generally having fun. Older couples promenade arm in arm and families with toddlers on little bikes or in motorised toy cars crowd the streets, along with a number of European tourists.

All around the lake are impressive buildings, with modern skyscrapers and banks lit up, as well as colonial-era buildings. In fact, the centre of the city feels very much like an Oriental cross between Paris and NYC, with political propaganda statues and murals reminding us that we are in a communist state. One of the biggest statues is the Martyrs Monument but the most impressive is the enormous figure of the 11th century Emperor Ly Thai.

It’s from his era that the lake gets his name, for legend has it that Ly Thai was sent a magical sword from heaven and used it to drive the Chinese from Vietnam. After the war a giant turtle grabbed the sword and disappeared into the lake to restore the sword to its divine owners. And in the middle of the lake sits a tiny island with a pagoda on it, called Thap Rua, or Turtle Tower.

It’s cute, but more eye-catching is the red-lit bridge to Ngoc Son Temple, known as the Temple of the Jade Mountain, the most visited temple in Hanoi. The gates are closed tonight so I walk on past, lured by the banging dance beats and laser lightshow of a huge outdoor pop concert on the lake’s north shore. Turns out Korean music is absolutely huge in Vietnam, and performing tonight, in a free event sponsored by Heineken, is one of K-Pop’s identikit stars, backed by a troupe of dancers. The crowd all wave neon glow sticks and singalong, while I weave though them, making my way behind the stage and returning to the hotel via the western side of Ho Hoan Kiem just before midnight.

The following night I explore in a different direction, wandering through the banking district to find one of Hanoi’s most celebrated restaurants, Um Dam Chay. It’s super posh, and fully vegetarian, but the hotel concierge has managed to secure me a space at the last minute. The food is extremely tasty – a wonderful tom yum soup, fiery with chilli, followed by a roast tomato and tofu dish, complemented with a passion fruit mojito – and the restaurant is a good-looking mix of industrial concrete, brick, metal and wood with zen music drifting over the table.

It may be one of the chi-chi-est joints in town, but the bill is a ridiculously cheap £10, which is probably a fifth of the price you’d pay in London. I make a note to return here in a week’s time when I’ll be arriving back into the city but my companions that evening tempt me astray on an altogether more hedonistic experience of Hanoi’s nightlife...