National Basilica and Shrine of the Immaculate Conception
I even met His Holiness there.
The Air and Space Museum is pretty good. (X-15)
Me 262
MC 205
Bf 109.
Robert E. Lee's house at Arlington National Cemetary.
Gerorge Washington's sword at the Museum of American History.
Scaffolding.
Our Lord sucking His thumb.
Wright Flyer.
By the way, it seems the SDf is advancing on Azaz. It's not clear whether that includes the YPG or just Jaysh al-Thuwar.