Guanajuato, situated at 2,000 m. above sea level, developed from its four original centres, which became separate neighbourhoods linked by a sinuous artery that follows the narrow valley. Its spontaneous plan, which opens onto small squares and adapts as required to the topography, distinguishes itself from the plans of other cities of the New World because it lacks an orthogonal grid. In the middle of lush green hills, the monumental architecture of this little mining town, most of which is religious, is either Baroque in style (Notre-Dame Basilica, dating to the end of the 17th century, and the Church of San Francisco), or Churrigueresque (the Church of the Compañia of the 18th century). The numerous squares and the cobblestone streets, embellished with cast iron lanterns, are lined with whitewashed and brightly coloured houses.