Nik and Lijana Wallenda Successfully Tightrope 25 Stories Over Times Square

It seemed impossible ... but Nik and Lijana did it -- they walked a quarter of a mile across Times Square, 25 stories up and balancing the entire way on a tightrope.

The view looking down was incredible, and it was broadcast live on ABC. Thousands watched as Nik and Lijana met in the middle and he actually CLIMBED OVER HER -- around 18 minutes into the stunt.

It was especially daunting for Lijana, who broke almost every bone in her face after suffering a near-fatal fall a few years back.

She was more than confident Sunday night, having nailed the run-through 25 times in a row. Lijana sang biblical hymns and praised the Lord as she traversed the famous landmark, with neon lights glaring and the crowd roaring.

Nik and Lijana constantly talked with each other ... he especially offering words of encouragement to his sister. Their dad was in the control room, and Nik and Lijana seemed to draw comfort from that.

By the way ... the poles they held weigh 38 lbs!!!