Underground Cities

Mapping the tunnels, transits and networks underneath our feet

Mark Ovenden

• Publisher: Frances Lincoln
• Year: 2020
• Print ISBN: 9781781318935
• eBook ISBN: 9781781318942
• Topic: Technology & Engineering
• Subtopic: Technology & Engineering Research & Skills
• Index: Technology & Engineering

With over 60 per cent of the world’s population living in cities, the networks beneath our feet – which keep the cities above moving – are more important than ever before. Yet we never truly see how these amazing feats of engineering work.
 
Just how deep do the tunnels go? Where do the sewers, bunkers and postal trains run? And, how many tunnels are there under our streets? Each featured city presents a ‘skyline of the underground’  through specially commissioned cut-away illustrations and unique cartography. 

Drawing on geography, cartography and historical oddities, Mark Ovenden explores what our cities look like from the bottom up.
 

Europe

The pneumatic tube room in the The Central Telegraph Office, St Martin’s Le Grand, London, in the late 19th century.

Gibraltar

The riddled rock

The Gibraltar peninsular, commonly referred to by the British as ‘the Rock’, is a 426m-high (1,400-ft) limestone outcrop in a strategic position at the foot of Spain and overlooking the entrance to the Mediterranean Sea. Fought over for centuries and now home to 35,000 people, this landmass of just 6.8km2 (2.6sq mi) is riddled with natural caves and around 55km (34 miles) of man-made tunnels. That’s more than double the length of the roads on the Rock’s surface.

Archaeological findings at Gothams Cave suggests that Neanderthals lived on Gibraltar 50,000 years ago. Early humans followed, and both the ancient Romans and ancient Greeks considered it to be one of the Pillars of Hercules flanking the Strait of Gibraltar – the other being on the North African mainland. The Moors built a castle here in the Middle Ages, and in the fifteenth century the Rock was won by the Spanish nobleman Juan Alonso de Guzmán in the Ninth Siege of Gibraltar.

Following the 1704 Capture of Gibraltar by Anglo-Dutch forces, excavations were made in the rock to provide defences. Passageways were carved out to connect gun emplacements, particularly on the northwestern flank, facing the Spanish mainland. Ceded to Britain in 1713, the Rock faced several attacks from the Spanish, and so yet more defences were dug during the eighteenth century. Construction happened in several phases, for example: the King’s Lines, built during the 1620s on passages already started by Moorish troops; the Prince’s Lines around a century later; and the Queen’s Lines, begun in 1788. The lines were effectively trenches cut into the rock and protected by walls. Full-scale tunnels, sometimes called the Upper Galleries, were created by the British Army during the three years of The Great Siege of 1779–1783, when France and Spain joined forces in an attempt to oust the Brits, providing access to an otherwise innaccessable strategic outcrop at the northern end of the Rock. Gibraltar subsequently became a major base for the British Royal Navy, serving key roles in most of the biggest battles of the following centuries.

Another substantial phase of tunnelling took place between 1880 and 1915, providing access from Camp Bay to a quarry via the 1km-long (0.6-mile) long east–west Admiralty Tunnel (1883), and to two enlarged caves under Windmill Hill that were used to make an ammunition storage facility.

Clean water

During the nineteenth century, much excavation provided for desperately needed waterworks, including reservoirs that were made inside the Rock itself. Owing to a growth in population, the traditional method of collecting rainwater in a dishevelled array of cisterns and barrels led to regular outbreaks of diseases such as cholera and yellow fever. It is said that there was not a single clean water pipe in the town until as late as 1863.

Towards the end of the nineteenth century, the shortage of clean drinking water had become so acute that crude desalination of seawater was introduced. In the meantime, concrete underground water-catchment and storage tanks were created on Upper Rock and Sandy Bay. By 1903, 40,000m2 (430,500ft2) of exposed rocky slopes had been covered with iron sheets to direct the precious rainwater into channels and stores. At its peak, more than 243,000m2 (2,620,000ft2) of the terrain had been used for this purpose, but the system was discontinued in the 1990s and the rocks returned to their natural state. Today the drinking water is supplied by a dozen reservoirs buried inside the rock itself. The reservoirs were constructed at various times between the 1890s to the 1960s, and some are open to visitors; one even has an ornate balustrade walkway. A modern desalination plant now supplies 90 per cent of the potable water to the reservoirs and the remainder comes from rainwater-capture schemes.

Artist’s impression of the Great Siege Tunnels. When captured Commander Duc de Crillon was shown the fortifications, he was so impressed that he conceded: ‘These works are worthy of the Romans’. They are now a major tourist attraction to Gibraltar visitors.

A strategic base

Gibraltar’s strategic location came into stark focus during the Spanish Civil War (1933–45) and the onset of the Second World War, during which it played a pivotal role. Almost the entire civilian population was evacuated and the Rock effectively turned into a fortress. It was from this time onwards that the lion’s share of tunnelling was carried out. Waterworks, air-raid shelters and an underground hospital were built and the total length of tunnels increased from 8 to 11km (5 to 6.8 miles). From 1939 this soared to 40km (25 miles) when new space was created to house an entire garrison of troops, effectively creating an underground city.

Following military traditions, main thoroughfares were named after major British roads and included Fosse Way and Great North Road. AROW Street was named in honour of Lieutenant Colonel Arthur Robert Owen Williams of the Royal Engineers. Facilities included a bakery, a telephone exchange, a power station and enough space to store food and water for the 16,000 troops stationed within.

Many wartime constructions remained secret until long after hostilities had ceased. One of the most recent discoveries, made in 1997, was a so-called ‘stay behind cave’, which would have been staffed by six dedicated personnel who were to remain on the Rock in the event of a successful enemy invasion.

In response to the Cold War, a final phase of tunnelling happened between 1956 and 1968. Two more water reservoirs and a fuel-storage facility were created and the last, Molesend Way, was completed in 1967.

While many of the tunnels, including AROW Street, have been decommissioned and sealed off in recent years, many others – for example, the Upper Galleries and Second World War tunnels – are open to visitors. Two others, Dudley Ward Way (now closed) and Keightley Way (the last major one to be built) were assumed into the road network.

Madrid

Mazes and metros

The third-largest city in mainland Europe, the Spanish capital has a population of 3.3 million, with a further 3.5 million in the wider metropolitan area. It also has the continent’s biggest underground metro system after London’s.

Inhabited since prehistoric times, the seven hills on which the modern-day city of Madrid stands boasts Celtic, Roman and Visigoth remains. A riverside fortress from the mid-ninth century was built during Moorish rule and Christians took over in the eleventh century, leading to Madrid winning city rights in 1188. By the 1500s, there were already 30,000 inhabitants and the Spanish royal court moved to here from Toldeo. Railways arrived in 1851 and the population exploded, reaching half a million by the 1890s and topping a million by 1940.

Subterranean curiosities

From the tenth century onwards, the Moors built a canal network inside the hills, for water supply. Further tunnels were built in the hills to store food or weapons, as wine cellars, shelters or in some cases prisons. Some of these are known to have been deliberately carved out during the 1400s as secret escape routes from religious sites, palaces and military establishments. Up to 145km (90 miles) of ...

Table of contents

• Cover
• Title Page
• Contents
• Introduction
• North and South America
• Europe
• Asia and Oceania
• Honourable Mentions
• Further Resources
• Index
• Credits
• Copyright