Microsoft has bought online mapping company Multimap to expand its web business, the US firm said.
Multimap, which was established in 1996, is among the UK's top 10 visited websites, receiving more than 10 million users each month.
Microsoft hopes that the acquisition "will play a significant role in the future growth of our search business".
Web search giant Google, Microsoft's arch-rival, provides its own online mapping service, Google Maps.
Microsoft's internet empire also includes services such as Virtual Earth, Live Search and Windows Live.
Earlier this year Microsoft bought a 1.6% stake in social networking site Facebook for $240m (£117m) and US online advertising firm aQuantive for $6bn.
It has not revealed how much it is paying for Multimap.
Sharon Baylay, general manager of the Online Services Group at Microsoft, said that the deal with Multimap presented "a huge opportunity to expand our platform business beyond the UK and globally".
Multimap has offices in America, Australia, South Africa and Turkey, as well as in London, and has a presence in 48 countries.