ShiKahr was a major city on Vulcan, located on the edge of Vulcan's Forge and ten days travel, on foot, from the L-langon Mountains. (TAS: "Yesteryear")
ShiKahr is the location of the ShiKahr Academy, where Tolaris taught prior to his becoming a V'tosh ka'tur. (ENT: "Fusion")
Future Starfleet officer and Federation Ambassador, Spock, was born in ShiKahr in 2230. Sarek and Skon, Spock's father and grandfather, were also both residents of Shi'Kahr. (ENT: "Two Days and Two Nights"; TAS: "Yesteryear")
A holoprogram available to crewmembers of the USS Enterprise-D featured a "Shi-Kar desert survival" on Vulcan. (TNG: "The Emissary")
The USS ShirKahr was named after the city. (DS9: "Tears of the Prophets")
ShiKahr, as it was spelled in the script for "Yesteryear", has also been spelled "Shi'Kahr", "ShirKahr", "Shirkar", and "Shi-Kar".