Santi Gregorio e Siro, Renaissance parish church in Porto district, Bologna, Italy.

Santi Gregorio e Siro is a Renaissance parish church located in Bologna's Porto district. The building features a simple stone facade and a bell tower adapted from medieval foundations, with multiple decorated chapels and artworks filling the interior space.

The first stone was laid on 20 June 1533 for the Canons Regular of San Giorgio in Alga, on land taken from the Ghisilieri family after their expulsion in 1445; the church was consecrated between 25 January and 1 February 1579. A 1779 earthquake damaged the vault and facade, and Angelo Venturoli gave the building its present neoclassical forms. In 1798 the convent was confiscated and sold, while the church stayed open as a parish.

The name combines two saints whose images appear throughout the interior, reflecting the local community's spiritual traditions in the Porto neighborhood. The artworks adorning the walls and altars serve as visual storytelling for those who walk through the space.

The church sits centrally in Bologna along Via Montegrappa and is easily reached from the main roads in the Porto district. The bell tower with its chimes makes it straightforward to locate the building from a distance.

The physicist and biologist Marcello Malpighi, who died in 1694, is buried inside the church. He was a professor at the University of Bologna and a pioneer of microscopic anatomy, and the Malpighian corpuscles and tubules of the kidney and spleen are named after him.