Answer

There is no single universally accepted “biggest” Jain tirth.

• If you mean most important pilgrimage site, Shatrunjaya (Palitana) in Gujarat is among the greatest Jain tirths.
• If you mean most sacred, Shri Sammed Shikharji in Jharkhand is extremely revered, especially by many Jain traditions.

Explanation

“Biggest” can mean different things in Jain Dharma:

• Largest temple complex
• Most visited pilgrimage site
• Most spiritually important tirth

Because of this, Jain devotees usually speak of great tirths, not just one “biggest” tirth.

Spiritual Understanding

A tirth is sacred not only because of its size, but because it helps the soul move toward vairaagya, bhakti, and moksha-marg.

Takeaway

If you mean the most famous Jain tirth, Palitana and Shikharji are the names most often remembered.