Which version of android OS support 64-bit architecture

As per my knowledge only the latest Lollipop (Android 5.x) OS is build to support 64-bit architecture. Are any older version of Android OS (prior to Android 5.x) also supported on 64-bit architecture?

Solution

Quick check of the Android Compatibility Definition Document for Android 4.4 section 3.3.1 states:

MUST report, via android.os.Build.CPU_ABI, only one of the ABIs listed below 
    * armeabi-v7a
    * x86
    * mips

And if you check Android Compatibility Definition Document for Android 5.0 you'll see in section 3.3.1:

* MUST support the equivalent 32-bit ABI if any 64-bit ABI is supported
* MUST accurately report the native Application Binary Interface (ABI) supported by the device, via the
    android.os.Build.SUPPORTED_ABIS, android.os.Build.SUPPORTED_32_BIT_ABIS, and
    android.os.Build.SUPPORTED_64_BIT_ABIS parameters, each a comma separated list of ABIs ordered from the most to the least preferred one

So the answer would be a definitive no, 64 bit wasn't supported before Lollipop 5.x. Or at least not at the compatibility API requirement layer exposed to apps.

Should you wish to check older CDDs they can be found here: https://source.android.com/compatibility/cdd