The Diplomatic Enclave is a sealed-off section of Islamabad east of the Red Zone — a quiet, leafy area containing nearly all foreign embassies, ambassadors' residences and the Serena Hotel. Access requires a visitor pass (your embassy or hotel can arrange one) and the enclave is fenced off from the rest of the city.
It is not somewhere you wander as a tourist, but visa-running travellers often spend long days here moving between embassies — for onward visas to China, Iran, India and the Central Asian republics. The Pak-China Friendship Centre at the south end of the enclave hosts conferences and concerts and is open to ticketed events.