Why is Tuesday the 13th considered unlucky?

Tuesday the 13th is widely regarded as an unlucky day in Greece, Cyprus, and several Spanish-speaking cultures, rooted in both historical events and numerical symbolism. The number 13 is often viewed as disruptive to the harmony of 12, while historical associations include the fall of Constantinople in 1204. Cultural practices and superstitions, such as avoiding marriage or travel on this day, have even inspired Greek cinema, notably the 1963 comedy film starring Nikos Stavridis.