High Quality Content by WIKIPEDIA articles! Epifanio de los Santos Avenue, (Tagalog: Abenida Epifanio de los Santos) commonly abbreviated as EDSA, is an important arterial road and freeway in the Republic of the Philipppines. The Avenue serves the National Capital Region, or the Metropolitan Manila, passing through 6 of the 17 settlements in the region, namely, the cities of Caloocan, Quezon City, Mandaluyong, San Juan, Makati and Pasay. It is the longest and the most congested highway and thoroughfare in the metropolis, stretching some 23.8 kilometres (14.8 mi) as it serves as a major north to south transportation corridor in the Metropolitan Manila.