A man sleeps between tombstones in front of his single-room home on a hot night in the Cairo Necropolis, Egypt, October 13, 2015. In the sprawling Cairo Necropolis, known as the City of the Dead, life and death are side by side. Amid a housing crisis in Egypt, and with the population of greater Cairo estimated at about 20 million, people count themselves lucky to have a place to call home in the graveyards that date back hundreds of years. (Photo by Asmaa Waguih/Reuters)

Kale grows at Kajodlingen farm in Gothenburg, Sweden, September 28, 2016. They are doing it on the rooftops, on tower block balconies and even on a disused railway: Swedes have discovered a passion for urban gardening as a way of growing fresh food and getting back in touch with nature. Part of a global movement, an increasing number of Swedish city-dwellers are growing their own in window boxes and allotments or are visiting public gardens built in or on industrial or office spaces. (Photo by Maxim Shemetov/Reuters)

These are the ambitious plans which suggest skyscrapers of the future may house an entire city. The Endless City project is an award-winning proposal by sure Architecture, who propose turning skyscrapers into complete ecosystems. London is the proposed city for the mixed-use tower – which would feature huge ramps linking different sections of the structure. The company, whose design won the SkyScrapers and SuperSkyScrapers Competition, insist the structure would be a great space-saver in dense cities which have previously spread outwards rather than upwards. (Photo by Caters News)

A busy rush hour sees thousands of commuters climbing on board a train – as well as holding onto its sides and sitting on the roof before it speeds off. Men, women and children climb and are pulled up onto the roof of the train, which is around 12ft (3.6m) high, as they try to find themselves a space. With no seats available inside, many commuters decide to take the risk and choose a rooftop view for their journey out of Dhaka city, in Bangladesh. (Photo by Yousuf Tushar/Solent News & Photo Agency)

A sewer cleaner of Dhaka City Corporation cleaning out the city's sewers on May 03, 2017 in Dhaka, Bangladesh. Despite a rise in the number of deaths of manhole workers every year, workers regularly go into the manholes without any protective gear. (Photo by Zakir Chowdhury/Barcroft Images)

A group of people perform yoga on the bank of the river amidst heavy fog on a cold winter morning in Narayanganj, Bangladesh on December 9, 2020. (Photo by Mushfiqul Alam/NurPhoto via Getty Images)

A gypsy man doing their traditional performance with a Cobra snack during the outbreak of coronavirus disease (COVID-19) at Savar the outskirts of Capital Dhaka, Bangladesh on April 24, 2021. The river gypsies in Bangladesh locally known as “Bede” community. (Photo by Fatima-Tuj Johora/ZUMA Wire/Rex Features/Shutterstock)

A village boy from Satla Village, Barishal swimmimg with water lilies in a canal near Barishal, Bangladesh on August 17, 2021. Every bright pink blooms is hand-picked and collected carefully by farmers to distribute in the local markets during a annual period. The flowers bloom during of the seasonal flood starting from August to November. (Photo by Mustasinur Rahman Alvi/Eyepix Group/Pacific Press/Rex Features/Shutterstock)