The London Underground is a marvel of engineering, opening in 1863 and carrying around 1.3 billion passengers along its 250 miles of track every year, through 270 stations.

But one of the most exciting developments for The Tube over the past few years has been the addition of Wi-Fi, starting in 2012.

Transport for London has confirmed that there's now Wi-Fi available at an additional 100 stations across the network, meaning a total of 250 Tube stations are now connected, offering Wi-Fi to passengers. 

It's a high-speed service too, with speeds up to 100Mbps. TfL tells us that a whopping 20TB of data is used every day, as Londoners stay connected on the move. That means that you can check your emails, update your social networks or, with the advent of VoLTE, make calls on underground platforms. 

You will have to register for the service with your mobile operator to get access of course, but once that's done, it's free to use.

If you're a visitor to London, Virgin Media offers pay-as-you-go access too. 

The list of newly added stations includes:

Alperton, Amersham, Arnos Grove, Barkingside, Barons Court, Becontree, Boston Manor, Brent Cross, Bromley-by-Bow, Buckhurst Hill, Burnt Oak, Canons Park, Chalfont & Latimer, Chesham, Chigwell, Chiswick Park, Chorleywood, Cockfosters, Colindale, Croxley, Dagenham East, Dagenham Heathway, Debden, Ealing Common, East Acton, East Finchley, Edgware, Elm Park, Epping, Fairlop, Fulham Broadway, Goldhawk Road, Grange Hill, Greenford, Hainault, Harlesden, Harrow & Wealdstone, Hendon Central, High Barnet, Hillingdon, Hornchurch, Hounslow Central, Hounslow East, Hounslow West, Ickenham, Kenton, Kew Gardens, Kilburn Park, Kingsbury, Latimer Road, Loughton, Mill Hill East, Moor Park, Neasden, North Acton, North Ealing, North Harrow, Northfields, Northolt, Northwick Park, Northwood, Northwood Hills, Oakwood, Osterley, Park Royal, Perivale, Pinner, Preston Road, Queensbury, Ravenscourt Park, Rayners Lane, Rickmansworth, Roding Valley, Royal Oak, Ruislip, Ruislip Manor, Snaresbrook, South Ealing, South Harrow, South Kenton, South Ruislip, South Woodford, Stamford Brook, Stanmore, Stonebridge Park, Sudbury Hill, Sudbury Town, Theydon Bois, Totteridge & Whetstone, Turnham Green, Upminster Bridge, Upney, Uxbridge, West Acton, West Finchley, West Harrow, Westbourne Park, Willesden Green, Wood Green, Wood Lane, Woodford, Woodside Park, and Victoria Coach Station.