1French money, Spanish name
The steps were funded by a bequest from the French diplomat Étienne Gueffier to link the French church of Trinità dei Monti at the top with the square below. The square was named after the Spanish embassy to the Holy See, and the name stuck to the steps too.
2The boat that's sinking on purpose
The Barcaccia fountain at the bottom, by Pietro Bernini and his son Gian Lorenzo, is a half-sunken boat. The water pressure here was too low for a tall jet, so they made a fountain that sits low and overflows.
3You can't sit on them
Since 2019, sitting on the steps can earn you a fine. The city brought the rule in after a costly restoration, to protect the travertine.