Somerville is considered to be a highly walkable and bikeable city. Houston's Museum District is walkable and bikeable. However, many consider Ithaca a walkable and bikeable community. They are comparably more dense than other suburbs and have lively, walkable downtowns. Like Old Town, many Alexandria neighborhoods are compact and walkable. More recently, Walk Score rated some Austin neighborhoods among the most walkable in Texas. The downtown has several overcrossings; Arcata is considered a fairly walkable community. The city centre is walkable and relatively flat. The walking bus depends on a walkable and safe built environment. It also creates a more walkable and bike friendly environment for residents. In 2011, Walk Score ranked Boston the third most walkable city in the United States. In 2011, Oakland was ranked the 10th most walkable city in the United States. In 2006, Tacoma was listed as one of the "most walkable" cities in the country. Campuses, in general, are fully walkable and sociable environments within the superblock structure. It would be tilted, rising up to eleven meters and walkable on special paths.