Belvedere Castle is the product of Calvert Vaux's imagination. It was built in 1869, and it overlooks the Great Lawn and Ramble. It used to be an open-air structure that housed the New York Meteorological Observatory, but since 1983, it has functioned as a visitors center and gift shop.

Amazingly, this dignified structure was not deemed a city landmark until 2010. It was built in the 1920s for the Headquarters Troop of the 51st Calvary Brigade, and its architects, Harold H. Werner and August P. Windolph, drew direct inspiration from medieval castles and fortresses. The National Guard still occupies the building today.

At the corner of Bedford and Atlantic avenues sits an imposing Romanesque Revival armory built in 1891-95. It was designed by local Brooklyn architects Fowler & Hough, along with Isaac Perry, the architect for New York State, and it functioned as an armory until the early 1900s. It was landmarked in 1977, and today it serves as a men's homeless shelter. [Photo by Jim Henderson via Wikimedia Commons.]

The Sumner Armory, also known as the 13th Regiment Armory, opened in 1894. Architect Rudolph L. Daus, designed the immense structure, and a watchtower used to soar above its round, 200-foot-tall towers, but it was cut down. It served military purposes until 1974, and sat empty until it was converted into a homeless shelter in 1987.

When Kingsbridge Armory in the Bronx opened in 1913, it was the largest in the world, and it served its original purpose until 1996, when it was turned over to the city. Like many other armories, it became a homeless shelter, but that ended after 10 years. Currently, redevelopment plans are in motion to turn it into the world's largest ice center.

New York State State architect George L. Heins designed the Flushing Armory in 1905 to look like a medieval European structure with "a five-story octagonal tower at the northwest corner and a three-story round tower at the northeast corner," according to Wikipedia. Currently, it is used by a NYPD task force. [Photo by Jim Henderson via Wikimedia Commons.]

Back when post offices were a respected and important part of everyday society, this impressive building was erected in Downtown Brooklyn. The design process start in 1885, and the interiors were not complete until 1892. The Romanesque Revival-style structure features arched windows, steeply pitched roofs, round granite columns, and a square corner tower.

This 5,000-square-foot "French Provincial" castle in Fieldston has been on the market for over four years. Despite its really neat kitchen turret, "whimsical breakfast room," and series of price adjustments (up as well as down), this $3.55 million house has failed to find a buyer who wants to bask in its imitation castle glory.

Originally, the Madison Avenue Armory, opened in 1895, occupied the entire block between Madison Avenue, Park Avenue, 94th Street, and 95th Street, but the western portion was demolished in the 1960s. The remaining parts are used by Hunter College High School and Elementary School. [Photo via PropertyShark.]

Today the Park Avenue Armory is one of New York's most unique cultural institutions, but the fortress was originally built for the Seventh Regiment by architect Charles Clinton in 1880. The brick Gothic Revival style building features a crenellated roof and occupies a full city block.

The city is currently seeking a developer to revamp this armory in Crown Heights. It's still used by the National Guard, but redevelopment plans would likely convert it into something for the community. It occupies nearly an entire block between Bedford Avenue, Nostrand Avenue, Union Street and President street, and its most prominent feature is the barrel-arched roof.

Lovers of lawn maintenance are flocking to this "magnificent Norman-style mansion" with expansive grounds in Riverdale, which is probably why its been on the market for nearly eight years. Other things people who settle here have to love taking care of include an 85-year-old house, 100-year-old carriage house, and an indoor and an outdoor pool. At least the property's asking $8.6 million, which is still a lot but is $4.1 million less than it was asking when it appeared on the market in 2007.

This building has more of a Hogwarts-style castle thing going on than a traditional castle thing, but it still counts. Dating to 1833, the Jefferson Market library building was designed by Calvert Vaux's partner, Frederick Clarke Withers, and it used as a courthouse until 1945. It almost went the way of the original Penn Station in 1956, but preservationists, bless their hearts, saved it. Today its delightful clocktower looks out over Greenwich Village.

The crumbling, landmarked former police precinct in Sunset Park has seen better days, but the property may get a new lease on life now that it's in the care of a mysterious developer. That is, in the care of a mysterious developer who refuses to disclose his plans for the property. Private mansion? Quite possibly—the property is zoned for residential use. But the community would rather see it used as a community space, and who can blame them? It was really quite grand when it was first built in 1886.

Castle Clinton does not look like a castle in the way that the other places on this list look like a castle, but it does have castle in its name, so it made the cut. Now a national monument located in Battery Park, this fort was built for the War of 1812. Some years after that, Castle Clinton was used as an opera house, theater, immigration center, and aquarium before being turned over to the National Parks Service in 1946.