The huge medieval church is impressive - they used to have vibrant speaches that got together plenty of people, that had to stand also outside the church, therefore friars were choosing such big Piazzas.
This square was famous also because here a lot of public games were held, for example the Calcio in Costume (soccer similar to american rugby), or Palio dè Cocchi, a race of 4 two-horses chariots roman style, much beloved by Granduc Cosimo I.
The façade is a very important example of Renaissance - the main artist, Leon Battista Alberti, could mix the already existant medieval façade of the first level with armony and semplicity, working superbly on marble inlaids, using the roman language of columns, geometric shapes such as circles, squares, triangle etc.
Inside, you will be absorbed by a solemn calme and peace - you would admire masterpieces such as Giotto wood crucifix, or Masaccio Trinity, and of course the spectacular chapels frescoed by Ghirlandaio and Filippino Lippi, just to mention some...
Right behind, there is a place that I love in Florence, the Spanish Chapel and the Green Cloister - a pearl, hard to find in Florence, no crowds of people, colourfull and interesting frescoes, dedicated to the Dominican friars history.
Don't forget to visit in Via della Scala 16 the Officina Profumeria Farmacia Santa Maria Novella, famous all over the world for its products, creams, parfums and so on...
The beautiful façade