NBC is getting ready to add to its Gotham real estate holdings: It plans to erect a giant treehouse at the corner of Broadway and 51st Street to tubthump the Oct. 17 debut of its drama series “Crusoe.”

The treehouse will be a replica of the high-rise digs where Robinson Crusoe lives in the latest adaptation of Daniel Defoe’s novel about a Brit who is shipwrecked on a deserted island.

Series stars Philip Winchester, who plays Crusoe, and Tongayi Chirisa, who plays his native pal Friday, will make appearances at the treehouse on Thursday as part of a satellite media tour. The treehouse site is conveniently located not far from the Peacock’s 30 Rock HQ.

In addition to the gee-whiz value for Gothamites, Peacock’s entertainment marketing unit aims to capitalize on the stunt with a website, Savecrusoe.com, that will feature a 24-hour webcam stream of the goings-on in the treehouse, as well as polls and contest giveaways of Microsoft Zune and Xbox devices.