Originally, Cha Pa was created for medical purposes: the bracing climate of Cha Pa was beneficial to westerners exhausted by a long stay in Vietnam, especially «people with chlorosis, post-infectious anaemia, previous history of malaria, and a whole array of neurotics: people with neurasthenia, phobia, overworked people or hypochondriac women». Certain diseases, such as «chronic bronchitis with associated emphysema or asthma and certain skin diseases» could also be cured. The military sanatorium, completed in 1913, was built on the hill on which the municipal cistern and its pumping station now stand.

As of 1914, the main purpose of the civil authorities was to create in Tonkin a veritable summer capital in the mountains. In the summer of 1914, the offices of all the local services were moved from Hanoi to Cha Pa. The works had started in 1912, the tourist office was created in 1917 and in 1925, there were already 80 kilometres of footpaths offering a great variety of hiking trips. The forestry service planted evergreens, some of which are still standing today. In 1922 the building of the most sumptuous hotel in the station, the Residence du Tonkin started on «governor's hill».

In 1909, thanks to Mieville, the « Cha Pa Hotel » was inaugurated to the east of the station on the road to Lao Cai, while the «Fan Si Pan» hotel was only built in 1924. The « Metropole », a luxury hotel with 50 rooms and ten suites sited at the foot of the Ham Rong on the bank of the lake, was inaugurated in 1932. The «Hotel du Centre», a more modest establishment, was built in1937.

The first villas were built in 1918 by the Hong Hai Coal Board and by the Ha phong cement factory (at the place where the Victoria Hotel now stands). A hundred or so other villas were built between 1920 and 1940 on neighbouring land given for free, some specimens of which can still be seen. In the lower area are located the private villas, administrative buildings and hotels. In the higher area, one finds the big military sanatorium and the governor ˜s summer palace. The church was built in 1934, followed by a protestant temple sitting on the hill overlooking the road to Cat Cat. By the end of the 1930s, Cha Pa had reached its peak and over a thousand colonials went there to rest and have fun. Until the mid-40s, Cha Pa was to remain the fashionable mountain resort of the Hanoi colonial society.

In order to meet the increasing demand for food, the local authorities created agricultural stations. The aim of these stations was to feed the summer visitors and « put an end to the typical problem of hotels where bread is wanting because a party of six had the unfortunate idea of turning up without sending a telegram two days earlier ». Vietnamese people launched into agricultural production, providing the town with « all sorts of foods »... The Taphin estate produced pork, chicken, vegetables, fresh fruit, jam, milk, potatoes, cheese and¦ wine. Trade was flourishing in the hands of Chinese people and Vietnamese from the delta area.

The growth of Cha Pa was an incentive to modernisation and between 1924 and 1927 the public authorities had it equipped with running water, a sewage system and an electricity network supplied by a power station built on the Cat Cat waterfall, whose renovated buildings are still in operation, as well as a telegraph and telephone network. In 1942, untypically for such a small place, a complete town plan of Sa Pa was drawn, which included over 400 plots of building land.

In February 1947, the Viet Minh attacked Cha Pa and destroyed the military installations and part of the hotels (among which the Metropole) as well as villas. In March, the Foreign Legion occupied Cha Pa again until October 1949 when the French troops left the region for good. In March 1952, the French headquarters ordered the air force to bomb the town. The Governor's Palace, the sanatorium complex, public buildings and most of the villas were destroyed. The Vietnamese population fled the ruined town and did not return until the early sixties. Not until the early 1990s did Sa Pa start developing again.