From my post of a week ago, the answer, of course, was the Royal Observatory in Greenwich, built in 1675.
That's Greenwich in London, by the way, not Greenwich in Sydney, which technically didn't exist in 1675.
The spot is infamous for Greenwich Mean Time (GMT), and in another link with Sydney, the time ball still drops every day to help you synchronise your watch to 1pm.
Nice work if you got the answer.
Funnily enough of the first three correct responses two were from people living quite nearby in London (and the other was a Pom).
The Observatory famously overlooks the River Thames and many of London's most noteworthy buildings.
Including, from left to right: The Shard, The 'Walkie Talkie', The 'Cheesegrater', The 'Gerkin', and Tower 42, before scanning around to Docklands, Canary Wharf, and just out of shot to the right, Greenwich Power Station.
The risk of a Brexit-induced recession has "all but evaporated" (Markit), with the UK Services PMI gauge notching a beat at 52.6 for September.
The perennially undersupplied London property market has seen transaction volumes fall quite sharply, while the higher (£925,000+) end of the market is hurting in response to punitive stamp duties.
An impact of this has in part been to push demand into lower-priced boroughs, particularly for investors who are now clobbered at a ridiculous rate of SDLT above £925,000.
We've already witnessed a spike in interest from non-resident buyers interested in the currency play - and foreign capital plays a significant role in London property - as the pound touched another 31-year low against the dollar today.
For a free copy of our Greenwich Borough report, please email firstname.lastname@example.org