One of the main activities of the day is located in the district of La Ribera in Ciutat Vella, which receive the Rey Carnestoltes (The Carnival King) with a great party.
Another activity of the day is concentrated in the Mercat de la Concepció in Arago Street, which hosts a tortilla (omelette) contest which rewards the most original.
On Sunday, February 10th, there are many Kid's activities starting from 17:00 at Passeig del Born. Like Mask dance or a balloon and confetti war.
At home, that day is usual to eat sardines. If you are staying in an apartment you can go for example to the Boqueria market, and buy sardines. Grilled are exquisite and it's a very economical dish, Bon Profit! Bon Appetit !
I hope you enjoy the Carnival!