In the hotel world, it doesn’t get much bigger than Marriott International. Founded by J.W. Marriott and his wife in 1927, the company transformed from one root beer stand in Washington, D.C., to about 3,900 properties in 72 countries, and 18 brands, from the Ritz-Carlton to the Residence Inn. It is the largest hotel company in the U.S. and No. 230 on the Fortune 500. For a time it was slow to act as the company’s peers expanded abroad, updating properties for younger, hipper travelers. That has changed. Marriott is now playing an aggressive game of catchup and has plans to open one hotel in Asia, on average, every eight days between now and 2016. Through an acquisition agreement reached in January, it is set to become the largest hotelier in Africa. And with Edition, Marriott is moving into the boutique space. Executive vice president Anthony Capuano says it’s the “marathon, not the sprint” that Marriott aims to win.

Out with the old

Many young travelers view Marriott as the preferred hotel of their parents’ generation but perhaps not their own, says global brand officer Brian King. The hotel chain is at the tail end of a renovation campaign — for both the Marriott and Courtyard brands — to change that perception. In 2007, King says, the lodging giant invested more than $1 billion to reinvent its lobbies for the “on-demand generation” that expects to have every amenity at its fingertips — adding more places for guests to watch the game, grab a bite to eat, drink a beer, or work on their laptops. The company also spent more than $5 million to research and develop ideas that make travel easier, like allowing customers to check in and out with their smartphones.

In with the new

In 2007, Marriott partnered with famed hotelier Ian Schrager — who is credited with inventing the boutique hotel category — to create Marriott’s Edition, which launched in Istanbul in 2011 and opened in London last year. Marriott now plans to bring the brand to North America with a location in Miami Beach coming in the fall and two locations in New York City, one launching in 2015 and the other in 2017.

Additions abroad

Marriott owns about 10% of the room share in the U.S. and roughly 1.5% of hotel rooms internationally. In 2012 the company made a $1.9 billion investment to dramatically increase its presence abroad. In January, Marriott finalized an agreement to acquire one of the largest hotel groups in Africa, Protea Hospitality, with 116 hotels and more than 10,000 rooms in seven countries. It plans to double its presence to 50 Chinese cities by 2016. The company’s executives say they continue to see potential for significant growth in continental Europe, where they are committed to opening 150 economy-tier Moxy hotels by 2024.

This story is from the February 24, 2014 issue of Fortune.