Drink a frozen margarita where the machine was invented
A converted soft-serve machine, 1971
A long-running family Tex-Mex restaurant, and the origin point of the frozen margarita as a machine-made drink rather than something shaken to order.
Why it's unique
On 11 May 1971 Mariano Martinez put the first frozen margarita machine into service here: a soft-serve ice cream machine rebuilt for the purpose, because customers kept complaining that hand-shaken margaritas came out watery and inconsistent.
The machine itself is now in the Smithsonian's National Museum of American History. The drink it created is served in every Tex-Mex restaurant on the continent, and this is the family restaurant where the idea was worked out.
Before you go
Be clear-eyed about what you are visiting: the original Greenville Avenue room is not the one trading today, so this is the family's restaurant rather than the exact spot, and the original machine is in Washington.
Order the plain frozen margarita rather than a flavoured one. The whole invention was about achieving a particular texture consistently, and a mango version tells you nothing about why it mattered.