LONDON — London’s newest tourist attraction is perfect for underground explorers. It’s not ideal for the claustrophobic.

A visit to Mail Rail , a subterranean train network that once carried millions of letters a day across the city, involves a cramped journey on a very small train through dark tunnels 70 feet (21 meters) belowground. It’s atmospheric, but confined.

“If you’re really tall, you may want to think twice before you buy a ticket,” Harry Huskisson, head of communications for Mail Rail and the related Postal Museum , said during a press preview this week.

For 75 years, Mail Rail was the subterranean circulatory system of Britain’s postal system. Trains transported letters, telegrams and packages between rail stations and sorting depots at speeds impossible on London’s traffic-clogged streets.

Its driverless electric trains — cutting-edge when the system opened in 1927 — whisked mail across a 6.5-mile (10 kilometer) stretch of the city, from Paddington in the west to Whitechapel in the east, at up to 35 miles an hour (56 kph.)

After decades when it was seen only by the engineers and letter sorters who worked on it, Mail Rail closed in 2003 as the rise of email sent the volume of paper letters — dismissively branded “snail mail” — plummeting.

Postal chiefs considered using the tunnels for parcel deliveries or to grow mushrooms. In the end, it was decided to preserve a section as a companion to the renovated Postal Museum. Mail Rail is scheduled to reopen Sept. 4 as a tourist attraction aimed at train buffs, postal fans and people who simply like to nose around formerly secret underground spaces.

Visits involve a 20-minute journey in a compact, glass-roofed train that passes through grime-encrusted tunnels and offers glimpses of disused platforms and a graveyard of dusty old wagons.

The ambiance is lively, rather than eerie. There’s informative audio narration, and several stops for films to be projected on the walls.

Sightseers who prefer to skip the close quarters on the trains can stay on the platform and watch a film of the journey. An adjacent display explains the history of the network and the people who worked there.

Like much of London, a city layered with history, the mail tunnels have undergone myriad uses. During World War I, when the tunnels had been dug but the trains were not yet running, the Rosetta Stone was brought from the British Museum for safe keeping in the hidden passage. Part of the site was turned into a replica Vatican for the 1991 Bruce Willis caper film “Hudson Hawk.”

Set underneath the Mount Pleasant sorting station in central London, Mail Rail sits across the street from the renovated Postal Museum, which charts the history of what curators eye-catchingly call “the first social network.” A single ticket — 16 pounds ($21) for adults — gains admission to both.

Tim Ellison, the museum’s deputy director, acknowledged that the name does not convey huge amounts of excitement.

“We quite like the challenge of the name Postal Museum,” Ellison said. “We want to change people’s perceptions.

“This is far more than post. It tells a story about human communication,” he said.

Opening to the public Friday, the museum takes a bright, interactive journey through the long — 500 years — and interesting story of Britain’s Royal Mail. Philatelists may be thrilled to see one of the only full sheets of the first-ever postage stamp, the Penny Black.

Even visitors with no special interest in stamps or postal services are likely to be intrigued when they learn how mail is woven into the fabric of history. It’s fascinating to be reminded, for instance, that the doomed RMS Titanic was an official mail-carrying vessel — the initials stand for “Royal Mail Ship.” When it struck an iceberg, it went down with 3,000 sacks of post as well as 1,500 passengers and crew.

The story the museum tells is laced with human connections and studded with violence, from wartime bombs to pirate attacks on postal ships to highwaymen’s raids on mail coaches.

Those for whom a short visit is not enough can rent out a brick-vaulted underground chamber at Mail Rail for parties or even weddings. There’s not much of a view, but the acoustics are fabulous.

“I think you probably have to be of a certain ilk to have your wedding in here,” Huskisson said. “And know your guests well.”


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