Update on 11/23/15: Stage one is missing and unlikely to stay in place if replaced. However, stage two - the final - IS in place and it's a nice little walk to get to it. Actually the walk is easier than it used to be because local mountain-bikers have created a network of trails so the terrain rating might be 2.5 now unless there's been a lot of rain. So here's the plan: you send your solved coords for stage one and we'll send you the field puzzle that used to be there. When you solve the field puzzle, you'll have the coords for the final.
So many good Unknown (mystery) caches are also Multicaches. One example: GCZ35Z The Gold Bug. We solved the puzzle for stage one, where we solved another puzzle to get to stage two where we solved another puzzle to get to stage three where we solved yet another puzzle to locate the cache. The Poe Gold Bug theme was followed throughout, so artistically it was a very satisfying series of puzzles while the hike prompted us to explore trails in a quiet gameland in southern PA. Perfect! This is only one of many memorable mystery multicaches we have found.
We'd love to hear about your favorite mystery-multicache adventures but don't want to ask you to list, say, 300 Unknown multicaches that you have found - and then have to check your list! Instead, we'll specify that in order to log this cache, you must have found 500 Unknown caches and 300 Multicaches. If your public profile doesn't show these statistics, please provide proof.
We also request (but don't require) that in your found-it log, you tell us about a particularly memorable Unknown cache that was also a multicache.
The given coords are for a convenient exit from the interstate highway. The coordinates for the first stage of this two-part mystery-multicache are here:
543 217 194 531 285 379 153 561 843 194 637 298 514 286 723 964 415 912 735 145 827 392 645 154 763 912 345 374 618 241 623 192 584 325 167 234 589 123 845 146 527 163 287 914 256 372 154 592 643 574 329 218 134 892 532 364 318 264 712 695 538 621 739 165 824 612 328 195 276 138 547 563 341 374 691 832 145 792 625 914 682 576 428 615 716 384 423 152 398 613 592 146 461 152 844 376 415 223 725 284 241 139 351 614 385 419 425 925 361 318 527 256 734 152 825 396 124 236 158 264 794 812 615 382 138 624 572 419 381 654 273 164 952 284 321 546 732 624 129 421 655 516 924 243 743 219 582 263 641 137 821 592 427 943 611 374 835 912 462 183 527 495 712 645 154 278 538 264 351 423 123 395 468 221 712 658 354 296 518 423 156 294 421 754 284 352 479 542 223 425 925 428 734 681 174 832 536 719 312 428 221 331 921 643 245 315 974 668 593 241 725 331 246 423 918 274 356 824 523 146 133 483 521 937 284 461 372 496 158 324 225 945 637 162 823 249 715 352 614 592 681 756 812 249 743 185 211 918 427 534 618 392 488 725 393 741 281 362 417 983 416 138 427 361 795 284 241 512 242 721 643 219 941 228 516 247 952 438 156 731 372 446 283 135
Some notes:
This cache cannot be used to meet the requirements of this challenge.
If you have not met the requirements of this challenge, you may visit this cache, sign the log book and post a note on this page. When you have met the requirements of this challenge, you may then post a "Found It" log without having to revisit the cache.
We have rated this cache a 5/5 because of what you have to do to meet the requirements for logging it. The find itself would be 5 difficulty (puzzle) and 3 to 4.5 terrain depending on your route. 
DEC has granted permission for this cache placement.
If you email the solved coords to us and feel ready to make the drive, we'll be happy to confirm that the cache is still in place and provide our phone number.
A well earned co-FTF for GuentherGal, Spatial Distortion and Uncle Fuzzy. Good job!