Marilao is situated at the southeastern part of the province of Bulacan, bounded by the city of San Jose del Monte on the east, municipalities of Bulacan and Obando in the west, Bocaue in the north and Meycauayan in the south. It lies 20 kilometers north of Manila, travel time is only about 15 minutes via the NLEX, and around 30 minutes via the Mcarthur Highway.
Marilao has 16 barangays namely: Abangan Norte, Abangan Sur, Ibayo, Lias, Poblacion l, Poblacion ll, Tabing-Ilog, Lambakin, Loma De Gato, Nagbalon, Patubig, Prenza l, Prenza ll, Sta.Rosa l, Sta. Rosa ll and Saog. The biggest in terms of land area is Loma De Gato and the smallest is Poblacion l. The town has a total land area of 3,374 hectares, it represents less than 1% of Bulacan’s total land area and is considered as the smallest municipality in the province. Of the total land area, 2.84% is government owned while 97.16% is privately-owned. Marilao is classified as a first class municipality and belongs to the fourth district of the province of Bulacan along with the municipalities of Sta. Maria, Obando and the city of Meycauayan .
Generally, the municipality is as a coastal plain near the shores of Manila Bay. The western portion covering barangays Abangan Sur, Abangan Norte, Poblacion I, Poblacion II and Nagbalon comprise the tidal flats while the other barangays comprise the hilly terrain of the town that generally rises up to the boundery with the city of San Jose Del Monte. Marilao has an almost uninterrupted inclining terrain that goes down from Loma De Gato to the tidal flats of Abangan Sur, Abangan Norte, Poblacion I, Poblacion II and Nagbalon
Marilao used to be a barrio of the then municipality of Meycauayan until it was founded as a separate municipality on April 21, 1796 through an official act of the Spanish government on the feast day of Mahal na Senor, then the patron of the municipality. The date was since then celebrated as the municipality’s foundation day, a non working holiday, commemorated with fitting ceremonies to highlight the municipality’s social, political, economic and religious richness it has so far attained.
The seat of municipal government, a two-storey building, was originally built in 1928 and underwent major renovation in the 1970’s. In 1998, another renovation was initiated, the façade adopted the “bahay kubo” motif to commemorate the centennial celebration. It sits on a 1,671 square meter lot located at barangay Poblacion l. The official hymn, “ Himig ng Marilao”, a composition of Eugenio Javier is sung in all appropriate public ceremonies and programs. The municipal seal has 16 stars representing the sixteen barangays, a sturdy animal - carabao, representing its hardworking people, the Prenza dam, a national structure built in the early 17th century for the Dominican priests and the wild yellow shrub called “luyang dilaw” in abundance during the pre- habitation years of the town from which the name Marilao was derived.
Other than the SM City Marilao located along McArthur highway in barangay Ibayo, other major municipal landmarks include the St. Michael Archangel Parish Church, a hundred year old spiritual edifice in Poblacion I and the Divine Mercy National Shrine in Sta. Rosa II. Being the tallest structures in the municipality the two churches are visible from many parts of Marilao, considered as “place markers” and serve as “points of orientation” to the local residents and visitors as well. http://marilao.gov.ph/about/default.asp
Unfortunately rhe river the cross Marilao was identified as one of the most polluted river by The Blacksmith Institute in October 2006. 
Marilao is politically subdivided into 16 barangays.
|Cities and Municipalities of Bulacan|
|Cities:||Malolos | Meycauayan | San Jose del Monte|
|Municipalities:||Angat | Balagtas | Baliuag | Bocaue | Bulacan | Bustos | Calumpit | Doña Remedios Trinidad | Guiguinto | Hagonoy | Marilao | Norzagaray | Obando | Pandi | Paombong | Plaridel | Pulilan | San Ildefonso | San Miguel | San Rafael | Santa Maria|