The exquisitely cobbled Plaza de la Catedral (Cathedral Square) was the last square to be laid out in Habana Vieja [1]. It occupied a lowly quarter where rainwater and refuse collected (it was originally known as the Plazuela de la Ciénaga—Little Square of the Swamp). A cistern was built in 1587, and only in the following century was the area drained. Its present texture dates from the 18th century.
Plaza de la Catedral is Habana Vieja at its most quintessential, the atmosphere enhanced by mulattas in traditional costume who will pose for your camera for a small fee. One Saturday a month, the plaza a venue for the Noche en las Plazas [2] espectáculo.
Links:
[1] http://www.moon.com/destinations/cuba/havana/sights-habana-vieja
[2] http://www.moon.com/destinations/cuba/havana/entertainment/nightlife/traditional-cuban-music-and-dance