The sports centre comprise Aarhus Skøjtehal (an indoor ice rink), Christiansbjerghallen (a sports hall), Idrætsdaghøjskolen IDA (a folk high school for sports) and full size outdoor association football fields. Katrinebjerg is a small neighbourhood within Christiansbjerg and is known for its IT center of IT-city Katrinebjerg ("IT-byen Katrinebjerg"). Begun in 1999, it is now the largest IT centre in Denmark and both IT businesses, administration and education are represented here. Riisvangen forms a larger residential area, comprised primarily by detached family houses. There are almost no shops, cafés or business, but the neighbourhood houses a sports club, Aarhus Fremad and their home ground, Riisvangen Stadion, next to which there are also facilities for tennis and athletics. There is also an area of allotments in the northern parts and easy access to the nature sites of Riis Skov and Vestereng. Trøjborg is located north of Aarhus C and to the east of Christiansbjerg, along the coast. Around 11,000 people are living here, with many university students. With its short distance to downtown and the nature of Riis Skov and the bay, Trøjborg has also attracted many non-students also. The borough works almost like an independent town-village within the city of Aarhus, having its own distinct architectural charm, shopping district and cultural life. There are about a hundred stores here, a cinema, grocery and fruit markets, plenty cafés, bars and restaurants and the supermarkets Løvbjerg and Rema 1000. The architecture of Trøjborg, presents a typical Danish working-class townscape from the late 1800s to early 1900s. The area underwent a modernisation from 2001 to 2006, with wider sidewalks, reconstructions of the urban space and a few new buildings. Marienlund comprise the northern tip of Trøjborg, near the traffic meeting point of Grenaavej, Nordre Ringgade and Dronning Magrethesvej. It is a residential area of mostly single houses with a distinct architectural design. Marienlund is also the name of a terminus for several bus lines going around and through Aarhus and it is the official gateway to the forest-park of Riis Skov. Riis Skov stretches along the coast of the bay and is a public forest-park now enclosed by the city.