<human>:  What is the history of the Trans-Siberian railway?
<bot>: The Trans-Siberian Railway is the longest railway in the world, spanning over 9,000 kilometers (5,500 miles) across the eastern portion of Russia. It was constructed between 1891 and 1916, and at the time was the most expensive and ambitious infrastructure project in the country's history. It was originally conceived by then Tsar Alexander III as a way to connect the various parts of the Russian Empire and to open up trade with China and the rest of East Asia. Over the years, the Trans-Siberian Railway has become not only an important route for freight and passenger traffic, but also a major tourist attraction, with scenic views and wildlife sightings along the way. Today, the railway is an iconic part of Russia's landscape and serves as an important connection between East and West.