Please answer a question about the following article about Kathmandu:

The National Museum is located in the western part of Kathmandu, near the Swayambhunath stupa in an historical building. This building was constructed in the early 19th century by General Bhimsen Thapa. It is the most important museum in the country, housing an extensive collection of weapons, art and antiquities of historic and cultural importance. The museum was established in 1928 as a collection house of war trophies and weapons, and the initial name of this museum was Chhauni Silkhana, meaning "the stone house of arms and ammunition". Given its focus, the museum contains many weapons, including locally made firearms used in wars, leather cannons from the 18th–19th century, and medieval and modern works in wood, bronze, stone and paintings.

When was the National Museum founded?
1928