A decade ago, if you made it big in the City of London, you bought a big family townhouse in Fulham or Chelsea and commuted in with the masses. Now, home, social and work life converge as the "City Fringe" – the mile or so around London’s financial hub, which includes Shoreditch, Hoxton and Old Street’s Tech City – becomes the newly hot place to live, and within walking distance of the office. 

Knight Frank now counts the City Fringe within their Prime Central London Index, having forecast in 2012 that property prices will rise 118 per cent by 2016. Supply is limited – just 408 new units were built between 2008 and 2012 and 650 are in the pipeline, according to Knight Frank – and demand is growing. Ben Babington from Jackson Stops & Staff says the high prices of west London, plus potential capital growth, attractive period buildings and the convenience of not having to commute is drawing buyers east to projects such as 353 The Strand, with four boutique apartments costing from £2.35m in a street rarely considered a residential address.

But for the ultimate trophy City property, they don’t come much glitzier than the two penthouses at The Heron. They ooze opulence with marble staircases, bespoke Boffi kitchens and "indoor outdoor" rooms with retractable roofs so you can pretend it’s Miami on hot days (and retreat beneath the glass ceiling for the rest of the year). But it’s what lies outside that really stops you in your tracks: views across the entirety of London which, from double-height, triple aspect living rooms with nearly six-metre glass walls, give the Shard a run for its money.

The residential tower, which was 97 per cent pre-sold before completion and provides a new home for the Guildhall School of Music and Drama, sits bang opposite the Barbican in the busy heart of the City. But from the 35th floor, where the 4,000 sq ft and 6,000 sq ft penthouses luxuriate (priced £12m and £18m), you rise above it all, soaking up your silent panorama of the capital. 

“The City is the safest place to live – there are security cameras everywhere and it’s the most heavily leased place in the country – so we see a lot of overseas investors buying for their children who are coming to university here. Some buyers work in the City, but some also reverse commute to jobs in the West End,” says Lisa Ronson, commercial director of The Heron’s developers, Heron International. “Restaurants and clubs are opening in the City all the time now, bringing a sense of life to the area.”

While we call ours the "City Fringe", in Manhattan, they’ve named their newly-trendy financial district "the FiDi". This classic New York neighbourhood of landmark historical buildings and waterfront parks is seeing a raft of ultra-luxury residential projects, including 75 Wall Street and condo-hotels 5 Beekman and 30 Park Place, to tie in with the completion of the World Trade Centre. 

“As major employers such as Conde Nast seek to move in and the re-envisioned South Street Sea Port attracts new retail, dining and entertainment, the financial district is poised for major economic growth over the next few years and residential developers are following suit. There are nearly two dozen condominium and rental projects in the works,” says Susan de França, president and chief executive officer of Douglas Elliman Development Marketing.  “It’s the fastest-growing residential neighbourhood in Manhattan. At 75 Wall Street, an investor recently paid £1,008 per square foot for a 440 square foot studio apartment,” she adds.

Candice Bruder, a PR consultant, has watched the FiDi evolve in her five years there. “It has emerged as a residential neighbourhood since Philippe Starck brought high design with 15 Broad Street and Armani followed suit with 20 Pine Street,” says Bruder. “I’m two blocks from most major subways, so commuting is a cinch, and as a post-911 incentive to buy in the FiDi, I only pay around $30 a year in property taxes. It’s also incredibly safe given the high security for Wall Street and the Federal Reserve in the area.”

For two of the world’s leading financial districts, it’s starting to no longer be a case of all work and no play.