Answer

In Jain tradition, Tirthankaras generally attain Keval Gyan in an open, natural place, not in a closed room. However, the most important point is that Keval Gyan is a spiritual state, so it does not depend on whether the body is indoors or outdoors.

Explanation

Keval Gyan means perfect and complete knowledge. It arises when all karmas that obscure knowledge are fully destroyed.

For Tirthankaras:

• They usually attain Keval Gyan while sitting in deep meditation
• Traditional accounts often describe this happening under a tree, in a forest, garden, or open sacred place
• It is generally not described as happening inside a closed room

So if we speak according to common Jain understanding:

• Historically/traditionally: outdoors or in an open place
• Spiritually: the place itself is not the cause; the cause is the complete destruction of karmas

After Keval Gyan, a divine assembly called Samavasaran is formed, where beings come to hear the liberated sermon.

Spiritual Understanding

Jain Dharma teaches that true knowledge comes from inner purification, not from external surroundings.

This means:

• A closed room does not prevent Keval Gyan
• An open place does not automatically produce Keval Gyan
• Keval Gyan happens when the soul becomes completely free from knowledge-obscuring karma

The open setting in scriptures and tradition also reflects:

• purity
• calmness
• natural simplicity
• freedom from worldly attachment

Takeaway

So, the simple answer is: Tirthankaras are traditionally said to attain Keval Gyan in open places, not in closed rooms, but the real cause is inner spiritual perfection, not the location.

If you want, I can also explain why many Tirthankaras are shown attaining Keval Gyan under a tree in Jain scriptures and temple art.