Budapest's most important museums are found on Castle Hill, in City Park, along Andrássy út in Erzsébetváros and in Southern Pest. The area surrounding the Parliament is home to the splendid Parliament building, as well as Budapest's most iconic church, the Basilica of St Stephen. Both Parliament and its surrounds and Belváros feature some of the city's best art nouveau architecture. Margaret Island and City Park are the city's most appealing green spaces, while the Buda Hills is a veritable playground for hikers, cavers and bikers. Óbuda is home to extensive Roman ruins and quirky museums, and Gellért Hill gives you some of the best views of the city.