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A Tale of Two Castles in the Thousand Islands

Boldt Castle and Singer Castle are two castles in the Thousand Islands that can be easily visited as part of a cruise or via your own boat.

Boldt Castle in Ontario Thousand Islands National Park

Thousand Islands National Park

At only 24.4 sq km, Thousand Islands National Park is one of Canada’s smallest National Parks, but what it lacks in size, it more than makes up for in scenery. Thousand Islands National Park consists of over 20 islands plus many smaller islets, 2 mainland properties, and a visitor center that is found in Mallorytown, Ontario. The Thousand Islands National Park is part of the Thousand Islands – Frontenac Arch, a designated UNESCO World Biosphere Reserve since 2002. Much of the park is only accessible by boat, and while we spent a full weekend camping in an oTENTik and day touring the gorgeous islands of the park, another reason for our visit was to see the castles in the Thousand Islands.

Family on muskoka chairs watch the sunset over Thousand Islands National Park.

Castles in  the Thousand Islands

Boldt Castle and Singer Castle are castles in the Thousand Islands. While they are, in actual fact, mansions rather than true, fortified castles, their opulence has seen them graced with the description. There are many residences in the area that could be considered castles in the thousand islands, but Boldt Castle and Singer Castle stand out far beyond the grand gardens, crystal pools and stunning architecture that you’ll find in the area. Since we had so much fun on our previous castle hunts in Jordan and Portugal, we jumped at the opportunity of visiting castles so close to our home.

How to visit Boldt and Singer Castles in the Thousand Islands

Both Boldt and Singer Castles in the Thousand Islands can only be accessed by boat. We booked a cruise via Rockport Cruises as at the time of our booking, it was the only boat operator in Canada that offered access to both castles as a day tour. The cost of the cruise also comes with a delicious buffet lunch.

Family on boat for their castles in the Thousand Islands tour.

Pro-Tip: The castles are also accessible via personal watercraft and have docks that are free to use for visitors paying for access to the islands. Both castles are located in American waters and there may be border agents present, so make sure you have your passport ready.

Boldt Castle

Boldt Castle is on Heart Island in the United States side of the St. Lawrence River. When you arrive you will immediately need to fall in line at passport control. The line moved pretty fast and after showing our passports, we entered the grounds of Boldt Castle. Since we were part of the cruise tour we bypassed stopping at the ticket booths and went directly to the grounds. We were free to roam the site and grounds but had to be back on the boat after 2 hours of exploring. So, before heading off we studied the map of the grounds to strategize.

Overview of Heart Island which contains Boldt Castle, one of two castles in the Thousand Islands National Park.

Pro-Tip: For those that want a tour, audio guides can be rented at the entrance.

Surrounding structures and the gardens

Besides the main castle, there are also other notable structures on the grounds such as the Alster Tower and the Power House can be accessed on Heart Island. Across the waterway on another island is the Boldt Yacht House (yes, they needed an entire island just for their boats!). However, separate tickets are needed to visit the Yacht House. Due to the limited time, we opted to stick to the main grounds and reserve visiting the Yacht House for another time.

Yacht House of Boldt Castle

As everyone was heading to the main house, we decided to head over to the Alster Tower first. Construction on the castle began in the early 1900s. The Tower was meant to entertain guests. This is evidenced by the dance floor that greets you as you enter the building. C and D had fun pretending to bowl at the onsite bowling alley. The Alter Tower is also commonly known as the Children’s Playhouse. During the time of our visit, the Playhouse was undergoing extensive renovations. However, we were still allowed to wander freely inside.

Alster Tower as viewed from the St. Lawrence.

Afterward, we explored the beautiful gardens and made our way towards the Power House. It is connected to Heart Island via a beautiful arched stone bridge. For a building whose primary purpose was to act as a generator station, its architecture is an absolutely stunning example of over-design. The inside is a basic museum of power equipment, but otherwise pretty spartan. For all its beauty, it can be visited in a few short minutes.

The Power House in the background and gardens in the foreground of Boldt Castle.

The main castle and the tragic story of George Boldt

From the Power House, we made our way to the main castle building. Construction of Boldt castle began in the early 1900s under the order of millionaire hotel magnate George Boldt. The castle was meant to be a summer home that he was going to give to his wife as a gift. However, Mrs. Boldt passed away suddenly just months before the completion of the castle and the heartbroken Mr. Boldt stopped all construction and never again set foot on the island. Because of this, Heart Island lay vacant for over seventy years.

Aerial view of Boldt Castle, one of the two castles in the Thousand Islands National Park.

Today, Boldt Castle and the Boldt Yacht House are owned by the Thousand Islands Bridge Authority. Inside the castle, the main floor and second level have been restored and furniture has been added to show what life would have been like in the castle. The upper levels of the castle remain unfinished. It’s interesting to wander around imagining what the various rooms could have looked liked. The contrast between the finished areas, and the areas with cracked ceilings and studded walls is amazing to witness.

Boy is admiring the stained glass ceiling in Boldt castle.

Pro-Tip: There is a theater inside the castle that shows a short movie about the history of the castle.

Singer Castle

The next stop in our castles in the Thousand Islands tour is the formidable Singer Castle. Like Boldt Castle, Singer Castle is on the United States side of the St. Lawrence River. Unlike Boldt Castle, there is no passport control on Dark Island. As the cruise docks on Dark Island, you are greeted by a tour guide. Singer Castle is privately owned, and visiting the island is a stark contrast to Boldt Castle. Singer Island strictly controls visits. You must remain with a tour guide at all times. Singer Castle is full of priceless works of art, literature, and history. Our group was divided into several groups with more or less 20 people.

Boy is admiring the stained glass ceiling in Boldt castle.

There was no wait time and the tour started straight away. We learned that Singer Castle was commissioned by the Bourne Family in 1905. Frederick Bourne was the fifth President of the Singer Sewing Machine Company, which is where the name “Singer Castle” came from. Because of this, many people donate sewing machines which we saw in almost every room of the castle.

A hidden door in the panel of the library at Singer Castle.

Pro-Tip: Singer castle is beautiful, but because of the strict access control, it may not be an ideal destination for spirited children. While C loved learning from the guide about all the incredible secret passageways, our time with D was spent trying to avoid destroying priceless artifacts.

Unlike Boldt Castle, Singer Castle was fully constructed. Until the 1960s the Bourne family spent their summers on the island. At the time, they called the castle, “The Towers”. The castle interior did not disappoint. D was excited to see all the knights and pointed them out every time he spotted one.

C liked peeking into the hidden passageways that were used by the servants to get around the castle. He just couldn’t believe that the walls held hidden doors that would open by pulling a book or pressing a secret button! There was one wing of the castle that we did not explore. This is because it was occupied. That’s right! A portion of Singer Castle is a bed and breakfast. The Royal Suite can sleep up to six people.

Final Thoughts on Visiting Castles in the Thousand Islands

Private boats are able to dock on the islands so it is not necessary to join a cruise. In retrospect, this would have been our preferred method of exploring the castles in the Thousand Islands. Firstly, for Boldt castle, we would not have been confined by the 2-hour limit. Then, we would have been able to visit the Yacht House. Secondly, for Singer castle, all private boats that arrive are still led around by a guide. However, it is more likely the tour will be private or at least very small, making for a more intimate experience. Have you visited the castles in the Thousand Islands? If so, how was your experience?

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Have you visited the Thousand Islands? What are your favorite things to do? Drop a comment below or tag our Instagram page in your photos. We would love to hear about your travels.

Wandering Wagars is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to,, Amazon and the Amazon logo are trademarks of, Inc. or its affiliates.

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Kendra Ratliff

Tuesday 8th of June 2021

My now husband and I absolutely fell in love with Boldt Castle! In fact, that is where we got engaged in 2018 and we just got married there in October 2020 during Covid.

Kevin Wagar

Tuesday 8th of June 2021

That must have been an incredible destination for a wedding! Congratulations to you both.

Jonathan Pitman

Saturday 5th of June 2021

We visited Boldt Castle in early May 2021, coming from Clayton, NY. We booked our boat tour there because we were staying in a hotel there, as opposed to Alexandria Bay. Honestly it didn't even cross my mind to take a boat from Alex Bay, which would've been a much shorter ride to the castle, but in retrospect, I'm glad I didn't. The hour long ride up the St Lawrence from Clayton was wonderful as we had a tour guide on the boat talking us through the islands, explaining who lived where, which celebrity owned which island, etc. as the captain weaved us in and out of them. My goal was to see the castle, and we did, but the unexpected tour of the Thousand Islands via boat was awesome!

Luke Crane

Friday 28th of January 2022

@Kevin Wagar, both of these castles are not in a Canadian national park. Both are in the US, and we’re built by Americans. Still very cool, but at the top of the article you state their in Canada, then later you admit their in America.

Kevin Wagar

Monday 7th of June 2021

The guides in the Thousand Islands are full of incredible information about the area and the fascinating people who have lived there.


Monday 22nd of July 2019

Many thanks for sharing. Will definitely visit summer of 2019.


Sunday 30th of October 2016

It looks like a nice day trip to do with kids! Although unfinished, I offer myself volunteer to live in the first castle for a while, the pool looks very cool!

Kevin Wagar

Sunday 30th of October 2016

LOL, contact them, maybe they'll be up for it!

Anuj Srivastava

Thursday 13th of October 2016

Very informative article and love those castles details. thousand islands is on our list for Summer's for sure.