The National Art Center is among the largest art museums of Japan and features only temporary exhibits. At the time of my visit there were nice exhibitions about modern architecture and paintings. The architecture of the museum is very modern and the facade is completely covered with glass panels. Access to the atrium is free and visitors do not have to but tickets for the whole museum but only for the exhibitions that they wish to visit. This museum is a must for those interested in art as it features diverse collections, whether modern or classical, which change over time.
Roppongi Hills is a building complex that caters all your needs, from lodging to restaurants and entertainment. The main tower, Mori Tower, is one of the tallest skyscraper in the city and offers a fantastic view of Tokyo from the observation deck.