No matter how thoroughly you plan out a construction project, there is just no guarantee that everything will go accordingly to that plan. It isn't just construction mishaps, scheduling, or delayed materials that cause problems, one of the biggest issues is that once you start digging, or breaking into walls and floors, you really don't know what you're going to find.

Here are 10 times that construction crews found some pretty insane stuff while working there way through a project.

1. 1894 Time Capsule

In 2015, Scottish construction workers were working on a section of the Ruthven Road bridge when they discovered a time capsule that had been sealed up in the bridge for over 120 years. When it was opened, they found a number of items including: a bottle of whiskey, a newspaper, and a scroll. The box and its contents were donated to the Highland Folk Museum.

2. Wolly Mammoth Tusk

Remember as a kid when you and your friends would try and "dig for dinosaur bones?" Apart from the odd arrow head or other indigenous artifacts, most of us came up empty. But the reality is that finding something ancient isn't all that uncommon. While working on the foundation of a Seattle residential building, workers found a 60,000-year-old mammoth tusk. The company responsible halted construction so that the tusk could be removed and preserved.

3. Un-exploded bombs

During World War 2, thousands upon thousands of bombs were dropped by all sides. Some of those bombs were either faulty, or for some other reason didn't detonate upon impact, so it isn't uncommon to unearth ordinances during construction projects. On Christmas day in 2016, a two ton RAF bomb was discovered in the Schwabian city of Augsburg in Bavaria. It forced the evacuation of over 50,000 residents.

4. Letter to Santa

In 2015, Lewis Shaw was helping to demolish a chimney in an old home. It was here that he found a letter addressed to Santa that had been placed there in 1943. It was written by a little boy named David and it was written as follows:

Dear Father Christmas,

Please can you send me a Rupert annual, and a drum box of chalks, soldiers and Indians, slippers and any little toys you have to spare,

Love

David

Lewis Shaw actually started a campaign to find the boy who wrote this letter, and wildly enough, he managed to find the man, now quite old, but still alive.

5. Forgotten Cemetery

This past March, construction crews were working around an apartment complex in Philadelphia when they accidentally found several dozen coffins, complete with intact human remains. It is believed that the bodies are from the 18th century because there was allegedly an old burial ground near by. When the First Baptist Church moved out of the area in 1860, they were supposed to re-inter all the remains of their past parishioners in their new location. Clearly someone thought they could get away with it.

6. Mayan Ball Court

In some of the more ancient parts of the world, you are bound to make some very random discoveries. In 2006, the ancient ruins of a Mayan ball court were uncovered while working on a housing project in Yucatan, Mexico. The court is around 2500 years old, and it has now become an important and protected cultural heritage site.

7. 18th Century Cemetery

New Orleans is a city steeped in history, with their own traditions regarding death and burial. Anytime that construction work is about to be done, residents and home owners understand and even sometimes expect to find the remains of people long gone. In 2011, Vincent Marcello wanted to build a new backyard swimming pool, but he new that there may be human remains on the property so he hired an archaeologist to come in and do an investigation before construction crews started digging.

Marcello's hunch was spot on, the archaeologist did in fact find 15 wooden coffins where the pool was to be located. The coffins were once buried in the much large Saint Peter Cemetery of New Orleans.

8. A Mansion From The Past

During the construction of a housing development in Wellington, England, workers found the foundation of a 12th century mansion. There was no previous information about the former home which is very strange as they were always historical records or deeds from that time period available. Archaeologists were called in, and though they did not find out any information about who may have lived there, they found a tile with a knight painted on it, similar to what had previously been found at Glastonbury Abbey.

This made the site much more important, but work continued on the housing development. All artifacts found at the site were sent to the museum for research and preservation.

What's the most surprising thing that you have ever found while working on your home?