Galeazzo Alessi (* 1512 in Perugia; 30. December 1572 ebenda) was an Italian architect influenced by the Roman High Renaissance, which meant that he combined lush architecture (arcades, loggias, staircases, vestibules and others) with landscape and thus became a pioneer of the Italian Baroque. He was probably a pupil of Gian Battista Caporali.
Alessi was enthusiastic about the architecture of antiquity. He copied the style, which helped him to fame all over Europe.
In Rome, where he studied from 1536 to 1542, he met Michelangelo Buonarroti, whose work influenced his style from then on.
From 1542 to 1544 he built the Paolina-Rocca fortress in Perugia, then Via Nuova and the church of S. Maria del Popolo.
From 1548 Alessi was a Genoese resident. One of his main works there is the new construction of the harbour with a guardhouse (1550), the Strada Nuova (today Via Garibaldi) with some of the most beautiful palaces of Genoa, also suburban villas with interesting staircases, and colonnades on slopes, as well as numerous churches. The main work among them is the church of Santa Maria Assunta dei Carignano, begun in 1552. Other examples of his art are Palazzi (Palazzo Municipale) and churches in Milan, some parts (church and monastery) of the Escorial in Madrid and numerous churches and buildings in Sicily, Flanders and Germany.
The young Rubens was so fascinated by his works that he made a series of drawings based on them, which were published in 1622 under the title Palazzi di Genova.
Alessi also designed the Basilica of Santa Maria degli Angeli (Assisi) in Assisi, one of the largest churches of Christianity (1568).