It is the sixth largest urban area in Western Province, after Colombo, Negombo, Kalutara, Panadura and Avissawella.

Gampaha has a land area of 25.8 ha (64 acres) and is home to the offices of 75 government institutions.

However, at present the location of Pattiyagama can no longer be identified within the town limits of Gampaha and remains disputed.

The 5th Governor of Ceylon, Sir Edward Barnes made a visit to Gampaha in 1825, on the way to observe the construction work of the Negombo-Colombo main road.

When British built the “Moragoda” catholic church in 1828, Gampaha and surrounding areas slowly became inhabited.

The town was planned in 1920, with 52 roads including the main street, a water tank, a public market, a hospital and an electrical generator.

Also some rural industries like pottery, tiles, hand loom textiles, coconut related products can be found.

[10] Pundit Wickramarachchi found the first Ayurveda College of the country - "Sri Lanka Siddhayurveda Vidyalaya"[11][12] in 1929 closer to Yakkala.

The institute offers "Bachelor of Ayurveda Medicine and Surgery" (BAMS) diploma and the practitioners are distinguished around the country as "Gampaha Ayurvedic Physicians".

Rules for the regulation of the professional conduct of Ayurvedic physicians have been approved by the Minister of Health and gazetted in June 1971.