All eyes on Amsterdam Ave.

Equity Residential is taking over a major stalled site on the Upper West Side for $76.5 million.

The Chicago-based company headed by Sam Zell signed a 99-year lease for the site, at 170 Amsterdam Ave., with American Continental Properties.

While transfer taxes were paid on the entire amount it is unclear if a yearly rental is also involved or if that is the total payment.

The 20,700-square-foot site is on the westerly side of Amsterdam Avenue between W. 66th and 67th streets. According to documents, the lot has at least 238,893 square feet of development rights.

“We did just sign an agreement with the intention of building a tower,” said Equity spokesman Marty McKenna, who declined to discuss the finances. He did tell us the new building will have about 8,500 square feet of retail and 230 apartments.

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One of the last remaining boutique rental buildings in the heart of the Upper East Side went into contract to be sold last week to Vornado Realty Trust for approximately $170 million.

The 1913-era building at 11 East 68th Street has two residential wings with a canopied entrance on E. 68th St. and 5,000 square feet of stores along Madison Ave. -- with 100 feet of frontage.

Retail tenants Malo and Joseph have leases coming up next summer, which made the building a duel target for prospective buyers that included the Cayre family, Howard Lorber, Area and Stonehenge. The retail alone was valued at around $75 million, sources said, while the apartments were pegged at $2,440 per foot, or $2.4 million per unit.

In a noteworthy play, two groups of bidders wanted to secure the 41-apartment property -- with 31 large apartments at market rents as high as $35,000 a month -- as an abode for “friends and family.”

Adam Spies and Douglas Harmon of Eastdil Secured marketed the building for the sellers, ABRO Management, which bought it in 2008 near the top of the market for $191.8 million and will have “a continuing interest.”

Five thousand square feet of additional air rights could also prompt a luxurious penthouse addition to a property where air-conditioner units still jut from walls.

Vornado has been active in both the retail and residential markets, previously converting 40 E. 66th St., and constructing the Beacon, aka Bloomberg Tower, at 731 Lexington, and is working on the teardown and new building at 220 Central Park South.

Also in the area, Harry Macklowe will convert his $253 million purchase of 737 Park Ave. and the $70 million 150 E. 72nd St. The Apthorp sale in March of 2007 holds the record at $426 million for 163 units at 390 West End Ave. and was marketed by Harmon.