While most of us would like to be able to take the famous black cabs around London on our vacations, it’s definitely not the most economical way to get around town. With the traffic, it’s not always the fastest way either. While the occasional cab ride works for most families or couples on vacation, there is a terrific alternative to hop around town.

London Travel Cards are by far the most cost effective way to get around London – and you can purchase these in advance from here in the States.

The passes are good for unlimited travel in Central London for a variety of different modes of transportation. Use your passes for the London Underground subway system (known as the Tube) and Dockland Light Railway (DLR), all buses with the London Buses logo, Tramlink, and National Rail trains except the Heathrow Express. Passholders are also entitled to a 33% discount on all scheduled Riverboat services.

To purchase 1, 3 or 7 day Travel Cards online with US dollars, visit Rail Europe here: BritRail & More.

It’s tough to quote fares here, because they are always subject to change, but it will cost you under $100 for a full week of unlimited travel. To put it in perspective, that’s about the same amount you’d spend for a single roundtrip tube ticket each day of the week. It’s a great value.

Prices are based on adult and child (a child is aged 5-15; be prepared to carry proof), peak and off-peak travel times, and on how many of the six Underground “zones” you will need. Most tourist attractions are within Zone 1 and 2 on the Tube’s system, so chances are good that you won’t need to buy the most expensive pass. If you plan to use the Tube to and from Heathrow, you can purchase separate tickets for either the regular service or Heathrow Express.

You can buy Travel Card tickets up to three months in advance. If you’re making last-minute vacation plans, you can purchase a Tube pass (known as an Oystercard) upon arrival. Of course, you can always purchase individual journey tickets for any of London’s means of public transportation.

Train travel outside of Central London can be also be planned and bought online in advance of your vacation. Both consecutive and flexible passes can be purchased, depending upon your schedule and what trips you’re planning outside of London. Click here to buy: BritRail & More.