Sacred Heart Cathedral is one of Algiers' most unusual modern buildings, a concrete Roman Catholic cathedral completed in the mid-twentieth century. Its ribbed, tent-like form is a sharp contrast to the Ottoman lanes of the Casbah and the French balconies of the lower city, which makes it worth seeking out if architecture interests you.
The building also says something about Algiers' layered religious and colonial history. It became the city's cathedral after the older Saint Philip cathedral was returned to use as Ketchaoua Mosque, so a visit fits naturally with a broader walk through the capital's churches, mosques, and civic monuments.