Shenzhen — City of Innovation (30-min)

Shenzhen sits directly across the border from Hong Kong's New Territories, and the MTR East Rail Line makes it one of the simplest international crossings anywhere: ride to Lo Wu, the line's northern terminus inside Hong Kong's border zone, walk across the Lo Wu Control Point into Luohu Port, and you are in a different country. The checkpoint is genuinely busy, in a widely cited 2012 count it handled around 240,000 crossings a day, and on the Shenzhen side it connects directly into Shenzhen Metro Line 1 at Luohu station and Line 9 at Renmin South, so onward travel across the city takes minutes rather than another taxi ride. The most photogenic reason to make the trip is Window of the World, a theme park in Nanshan District that opened in June 1994 and has spent three decades cramming around 130 scale replicas of the planet's best-known landmarks into a single afternoon: a one-third-scale Eiffel Tower rising 108 metres over the park, alongside miniature versions of Angkor Wat, Christ the Redeemer, the Pyramids of Giza, the Sydney Opera House, the Taj Mahal, a slice of the Manhattan skyline and Mount Fuji. It has carried China's top 5A tourist-attraction rating since 2007 and now draws more than 3.25 million visitors a year, with an indoor ski slope and a dinosaur-themed water park added on the side for anyone who tires of the landmarks. For something more grounded, the Shenzhen Museum in Futian District's Citizen Center holds more than 20,000 historical and cultural relics across four branches, including a Reform and Opening-up Exhibition Hall built around Deng Xiaoping's 1992 southern tour, the visit that cemented Shenzhen's transformation from fishing town to megacity, complete with the actual spade Deng used to plant a tree and the car he toured in. Crossing from Hong Kong into mainland China always means clearing a separate immigration checkpoint. Hong Kong permanent residents of Chinese nationality travel on a Home Return Permit rather than a passport or visa; permanent residents who are not Chinese nationals use a different mainland-issued travel permit. Foreign visitors have two visa-free routes worth checking before they book: nationals of 50 countries — most of Europe plus Australia, New Zealand, Japan, South Korea and several Gulf and Latin American states — can already enter mainland China visa-free for up to 30 days for tourism, business or family visits, under China's nationwide unilateral exemption policy. Nationals of a further 57 countries, including the United States, Canada and the United Kingdom, can transit through China visa-free for up to 240 hours if they hold a confirmed onward ticket to a third country or region and enter through one of the policy's designated ports; whether the Lo Wu / Luohu crossing is one of those ports should be confirmed against the current National Immigration Administration port list before relying on it. Anyone outside these categories needs to arrange a standard Chinese visa in advance.