U is for unión and universal

 We're up to the letter U, and here's a stamp from Spain commemorating the 150th anniversary of the Universal Postal Union in 2024. Founded in 1874, the UPU is based in Berne, Switzerland, and since 1948 has been part of the UN. If you're interested, the website for the UPU is here. 

Thanks to Eva for sending the stamp.

For more U stamps, explore the links at See it on a Postcard

And happy solstice!