[kosciusko51]

There is an A-12 (an SR-71 variant) outside of the NASA Space and Rocket Center in Huntsville, where you can get quite close to it.

[woodbutcher1963]

There is also a 1967 A-12 at the Intrepid Museum in Manhattan, NYC right on the West Hudson River. You can walk right up to it.

https://www.intrepidmuseum.org/AircraftCollection

[2CAVTrooper]

It’s the other way around. The A-12 predates the SR-71.

The SR was actually bigger than the -12 being about 6ft longer, carried about 1,000 pounds more payload, and more fuel.

But the cost for bigger size and weight was reduced speed (mach .35 slower) and a 10,000ft lower service ceiling.