The backyard of their brownstone might not have been large, but when these Brooklyn homeowners tilled up the soil to start a garden, they unearthed some big surprises, including old tools, an ancient bathtub, and this hole, which was probably a cistern. If you think you’ve found something valuable, have a pro appraiser assess your find and document the results in writing.

Related: Ideas for Reusing Old Items

Image: Pink Brownstone

Because urban abodes often have windowless common walls, many older buildings were built with centrally located air shafts to help bring light and air to interiors. Modern renovations often covered up these shafts, but they still work and can be a convenient way to run new HVAC ductwork and electrical cables. Be sure skylights or vent covers are in good repair and don’t leak conditioned air to the outside.

Image: Pink Brownstone

During renovation of a 19th-century brownstone, the homeowners tore out an old closet to discover it had been made from the bottom of an old dumbwaiter shaft.  Although the cart was missing, the gear and pulley system was intact. The shaft also housed gas lines. The homeowner says she would “love, love” to return the dumbwaiter to its original use, but they still need the closet space.

Related: Your Home’s Unsung Hero: The Closet

Image: Pink Brownstone

Believe it. When two young homeowners moved back to North Wales to take over an estate that had been in the family for generations, they were surprised to discover an entire servants’ kitchen hidden in the basement. The kitchen had sat undisturbed for decades, the entry sealed off from the rest of the house by piles of old junk, while 19th-century tables and cooking gear gathered dust. Check with your local historical society to determine the value of such a find.

Image: Cefn Park

A renovation of this sizable Manhattan house included removing a wall in an entry hall. Behind the wall: a mural by famed artist Keith Haring, who produced the work in the 1970s when he was a student and the house was part of the Visual School of Art. Not all hidden murals are by well-known artists, but if you discover one, check with a professional restoration expert to decide if the painstaking work of recovery is worth the one-of-a-kind character such a find gives to your home.

Image: Torsten Krines, Sotheby’s International Realty

An unexplained bump-out and a large vent opening were clues that a hearth was concealed in the wall of this cottage. A little tear-out work revealed a brick fireplace — not an unusual find in many older homes. Old fireplaces and chimneys should be thoroughly examined by a professional inspector or chimney sweep before they’re ready to use again; in some instances, new firebrick and a flue liner is needed to ensure safety.

Image: Moregous Blog

Demolishing a wall during the renovation of a bathroom revealed dozens of old razor blades. Apparently, the razor disposal slot in the old medicine cabinet emptied directly into a wall cavity. Prevent close shaves during renovation by always using caution — eye protection, dust masks, and gloves.

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Image: Alexa Fulper