Musement, one of Europe's modestly funded online travel agencies for tours and activities, is now part of the TUI Group.

The Italy-based startup was bought by the vertically-integrated travel giant this week for an undisclosed fee, although sources suggest the fee paid for the five-year-old business is in the "mid-range, double-digit" millions.

To date, Musement has raised .5 million in investment over the course of a number of rounds up to Series C.

It claims to have 1,100 cities worldwide offering 35,000 tours, activities and attractions.

Musement will sit within the TUI's Destination Experiences division - a part considered a "growth area" within the group.

TUI paid €110 million to acquire the Destination Management division of Hotelbeds earlier this year, giving it customer transfers, in-destination products for tour operators and customer tours.

TUI had previously bought U.K.-based consumer-facing tours and activities startup Isango in February 2013 for an undisclosed fee.