The bright-red cast-iron “pillar box” has an iconic status in British design history but it’s easy to stroll past one of the handy quirks found on many of them: the Post Office Direction Sign (Pods). These enamel plates were first introduced in the 1930s and feature helpful arrows guiding users to the nearest post office.

While they are inconsistently placed (and many have been damaged or stolen over the years), they are the legacy of a pioneering Royal Mail design programme. “Today the postal service is so fragmented that we don’t get design innovations such as the Pods,” says Steve Knight, curator of the Colne Valley Postal History Museum in East Anglia. Adds Julian Stray, senior curator of The Postal Museum in London, “Any remaining Pods are quaint and rather lovely survivors.”

Created by Copenhagen’s municipal architects in 1977, the dome-shaped lights suspended over the city’s streets helped to define the Danish capital. They rendered the streets lamp post-free and “optimised the use of urban space”, says Steffen Rasmussen, Copenhagen’s head of the Traffic and Urban Life department.

Last year, in a bid to become the first carbon-neutral capital, Copenhagen replaced 20,000 lamps with green models that will reduce energy consumption by 57 per cent. While their replacements are yet to be considered city icons, “the new street lights respect classic Nordic design”.

Neon signs lit up the Polish capital during the long years of communism, advertising everything from bookshops to dance halls but later fell into disrepair. Now Warsaw’s Neon Museum is working to preserve this heritage, restoring and relighting old signs.

“Young designers are once again creating electro-graphic art for shops, bars and restaurants,” says Ilona Karwinska, who co-founded the museum that is home to more than 200 signs. Neon is now a popular cause in the city: when a new neon sign was lit outside the Syrena Theatre last year, a crowd gathered to toast it with champagne.

Designed in 1968 by Slovenian architect Sasha Machtig, the curved, squat, modular forms of the K67 kiosk colonised cityscapes from Ljubljana to Skopje and all points in between. In the prime years of Tito’s socialist republic, K67s sold newspapers, fast food and flowers. They sheltered car-park attendants and locked together to form cafés.

Today, the K67 is not seen in such great numbers but it remains appreciated by Yugo-nostalgists and urbanists alike. “You can see it’s unique yet also a general design – it’s so flexible and simple,” says Hamburg-based architect Helge Kuhnel who set up a website to map the kiosks’ locations and encourage their preservation. “I realised that with the disappearance of the political system these kiosks might slowly disappear too. But it still fits our time; it’s not old-fashioned.”

Production ceased as Yugoslavia fell apart in the 1990s but the K67 remains in many of the region’s towns and cities – a reminder of a country that no longer exists.

At its busiest, Omotesando in Tokyo can be a seething mass of people. The best vantage point – and the speediest way to cross – is the pedestrian footbridge that runs from the police box in front of Ralph Lauren on one side to the Gyre building on the other. It’s also the place to stand if you want to take in the full sweep of the zelkova-lined street.

For architecture buffs the bridge offers the clearest view of Kazuyo Sejima’s translucent Dior building. Footbridges can be found all over Japanese cities, some more extravagant than others. The one in Tokyo that crosses the meeting point of Yamate and Inokashira streets has a lift on each of its four corners. Another, built in 1971 in Kikusui in Sapporo, is a perfect circle. These pedestrian overpasses may be taken for granted but they are a thoughtful and defining part of the city’s infrastructure.

The precise, multipurpose public signage that defines Argentina’s capital is the brainchild of one family-owned design agency. In the 1970s, Diseño Shakespear came up with the idea of replacing all-caps ceramic signs attached to walls with something easier to read.

Following the agency’s proposal, the city erected all-black street signs in sheet metal using white Helvetica Medium typeface. The signs, which were positioned on posts at intersections, came to include more information such as arrows showing the direction of traffic and house numbering for each block. “The city’s visual masterplan was extremely successful; 40 years later it remains efficient,” says Raúl Shakespear, one of the two brothers who founded the agency in 1958.

In 1995 the agency rebranded the city’s underground system. The new logo used the Frutiger font and assigned colours to different branches. Diseño also adopted the moniker subte – for Subterráneos de Buenos Aires. “Our design acknowledges the way people speak,” says Raúl.

A walk around Vienna offers a lush typographical history. Signage in the Austrian capital is often affixed to storefront façades, not painted on. This means that plenty of nostalgic signs have remained, displaying decades of styles and colours: from the golden lettering of imperial purveyors such as Scheer shoes to the 1950s neon of the pink-on-pink Aida café chain. Everyday suppliers such as electricians (imagine Elektro in pointy cursive neon) and pedicurists (Fusspflege) often put up signage too – and remarkably much of it is still around.

In 2012, lettering enthusiasts Roland Hörmann and Birgit Ecker founded an association called Stadtschrift (“city script”), the mission of which is to preserve old signage and its legacy. “We like letters and want to save them from disappearing,” says Ecker. On Kleine Sperlgasse in the second district the association has covered a vast wall with 13 outdoor signs dating from the 1920s to the 1970s as a kind of alfresco museum.