 The city in Biscay is composed of the titanium which protects the Guggenheim Museum Bilbao, designed by Frank Gehry, the glass which covers the entrances to the metro, designed by Norman Foster, or the steel which makes new urban development challenges possible such as the Isozaki Atea Towers by the Japanese architect Arata Isozaki, or Bilbao Airport by Santiago Calatrava.Another of the city's attractions is the neoclassical Arriaga Theatre.Right there is the start of the domain of the Old Town or Siete Calles/Zazpikale ("Seven Streets"), the old part of Bilbao with its Plaza Nueva (New Square), Santiago Cathedral and, at one end, the Ribera Market.