On Thursday, Iran's central bank devalued the rial by 8% against the dollar and ordered all currency-exchange shops to adhere to the official rate or be shut down, according to Iran's official media.

WSJ: Iran Blasts West Over Oil Embargo

So devalued is Zimbabwe's currency that the bank was forced to announce this week that it would allow some shops to trade in foreign exchange.

ECONOMIST: Can Zimbabwe's long-awaited power-sharing deal endure?

The project aims to attract local traders to the area to open businesses, set up pop-up shops and open a food court in the piazza in Exchange Square.

BBC: Croydon gets ?100,000 for Old Town market rejuvenation

In a bid to offset the impact of sterling's rise and remain competitive with duty-free shops abroad, Heathrow's shops are offering travellers who pay in various foreign currencies a more favourable exchange rate than the current market rate.

ECONOMIST: Midsummer madness

It works wonders, especially in shops, even if it does turn the purchase of a baguette into a five-minute social exchange.

ECONOMIST: Business travel