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This cache has been archived.

New Market Mallers: When this cache was published, the main purpose was to draw attention to an interesting and somewhat obscure piece of NYC history. Unfortunately, the city removed the oldest manhole cover in NYC and moved it to an unknown location. As such, I have decided to archive this cache.

However, since I love the location, I will be rebooting this cache with a new theme so that this great location and wonderful staff can continue to be part of the NYPL series. Thanks to all who visited and I hope everyone enjoys the new cache!


NYPL: Under Cover

A cache by New Market Mallers Send Message to Owner Message this owner
Hidden : 07/12/2016
2 out of 5
1 out of 5

Size: Size:   regular (regular)

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Geocache Description:

The manhole cover at the posted coordinates is New York's oldest manhole cover and used to allow access to the Croton Aqueduct, built in the early 1840's. The cover is stamped "1866".

***As of October 2017, the manhole cover has apparently been moved by the city. In the meantime, the questions below have been updated to reflect the replacement cover that is here now.

Welcome to the New York Public Library system! This cache has limited hours of availability, which are listed below on the cache page.

***NEW as of March 2017! Now geocachers who find at least 6 of the 12 NYPL caches are eligible for a pathtag! If you think you qualify, please send me a note and I will get your tag out to you.

Did you know that every branch of the New York Public Library offers free Wi-Fi? That's great news for all geocachers visiting from out of town!

Update: May 2017 - I have been notified by the New York City Geocaching Community that the NYPL Series of caches has won the award for Best Series in NYC in 2016!!

The Croton Aqueduct was a large and complex water distribution system constructed for New York City between 1837 and 1842. It was one of the first great modern aqueducts and transported water by the force of gravity alone 41 miles from the Croton River in Westchester County into reservoirs in Manhattan, where local water resources had become polluted and inadequate for the growing population of the city. Although the aqueduct was supplemented and largely superseded by the New Croton Aqueduct, which was built in 1890, the Old Croton Aqueduct remained in service until 1955.

The need for a new supply of fresh water was crucial and was prompted by the Great Fire of New York in 1835. In 1837 construction began on a massive engineering project, to divert it from sources upstate. The Croton River was dammed, aqueducts were built, tunnels dug, piping laid and reservoirs created. The gravity-fed aqueduct dropped 13 inches per mile. An elliptical tube, 8.5 feet high by 7.5 feet wide was laid with conical ventilating towers every mile or so, to relieve pressure and keep the water fresh. It extended from the Croton Dam in northern Westchester County to the Harlem River, where it continued over the High Bridge at 173rd Street and down the West Side of Manhattan and finally into a Receiving Reservoir located between 79th and 86th Streets and 6th and 7th Avenues. That site is now the Great Lawn and Turtle Pond in Central Park. The Receiving Reservoir was a rectangular tank, 1,826 feet long and 836 feet wide which held up to 180,000,000 US gallons of water. 35,000,000 US gallons flowed into it daily from northern Westchester.

From the Receiving Reservoir water flowed down to the Distributing Reservoir, better known simply as the Croton Reservoir, a fortified tank located on 5th Avenue between 40th Street and 42nd Street, where the main branch of the New York Public Library and Bryant Park are located today.

To find the geocache, you will need to REFERENCE some of the things you can see while standing near the manhole cover:

A = The number of words cut into the metal panels in front of the library.

B = The number of letters before the word SEWER appears on the manhole cover.

C = The number on the glass door across the street from the library.

D =The first digit in the number that you see to the left of the entrance to the library.

Please note the times that the cache will be available:

Monday 11am to 7pm

Tuesday 10am to 7pm

Wednesday 11am to 7pm

Thursday 10am to 7pm

Friday 10am to 5pm

Saturday 10am to 5pm

Sunday - cache not available

Additional Hints (Decrypt)

Cneg 1 - Wrefrl Fgerrg
Svany - ERS NOP.Q

Decryption Key


(letter above equals below, and vice versa)