Yes, the castle is the same as an ovservation tower. Other trails could get you there, but most direct is the Tower Path (marked dark grey on the map). I would say it's closer to a 45 minute walk each way. As others noted, the park remains closed for maintenance. Please see the DEEP or SGPA.org website for updates.
According to the website, the park is still closed from tornado damage, but I heard they're hoping it will be able to open this summer :(
Yes the castle is at top of the main trail has the lookout point from the top. Its an easy 30 minute walk. If you walk fast maybe only 20 minutes.
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