Kota Darul Ehsan Arch is a ceremonial gateway on the Federal Highway, marking the boundary between Kuala Lumpur and Selangor. Its Moorish-inspired arches and domes are a bit theatrical, but that is exactly why it has become a recognisable Petaling Jaya landmark.
You will usually see it from a vehicle rather than linger beneath it. For travellers interested in Greater Kuala Lumpur's urban geography, it is a useful marker of where the capital's sprawl becomes Selangor proper.