https://kriii.com/

There's an area with a glass floor where you can stand over the exact spot where they found his body.

There are also some Roman ruins in Leicester although I'm not sure if they've finished restoring them.

Bosworth Field, where Richard III was killed, is not far away and pretty interesting.

https://www.bosworthbattlefield.org.uk/

You might want to take a look at Coventry Cathedral, which is famous for being hit by bombs during WWII -- the old bombed out structure is still there, alongside a newer modern cathedral.

https://www.coventrycathedral.org.uk/visit/visit-coventry-cathedral

If you're going to go to Coventry, there's also Warwick, which doesn't have a cathedral per se, but does have a large collegiate church.

https://en.wikipedia.org/wiki/Collegiate_Church_of_St_Mary,_Warwick

And if you're going to go to Warwick, Kenilworth Castle is definitely worth a look:

https://en.wikipedia.org/wiki/Kenilworth_Castle

Finally, it's kinda far out of your way to the north west, but if you're interested in Roman ruins then Chester is a great place to visit. It still has much of the old Roman defensive wall around the main city center, in good condition -- you can walk on large parts of it. Plus it has a cathedral

https://chestercathedral.com/

Lots of great advice!

I have family in the Leicester area and just happened to talk to my mom and dad a minute ago, so they gave me some more tips for you:

If you're going to Southwell - pronounced "Suthel" - you're in the "Robin Hood" area, not far from Nottingham. What's left of Sherwood Forest is in this area. Southwell is also the home of Byron, apparently.

There's no cathedral in Nottingham, but there is a castle. Also near the castle in Nottingham is Ye Olde Trip To Jerusalem, one of the pubs which claims to be the oldest in England (opened in 1189).

https://en.wikipedia.org/wiki/Ye_Olde_Trip_to_Jerusalem

And if you're in that area, they highly recommended Lincoln Cathedral, which they say is one of the best cathedrals in the country. Lincoln is also an ancient Roman city.

https://en.wikipedia.org/wiki/Lincoln_Cathedral

I mentioned Warwick in my previous post but forgot to mention that it has one of the best castles in the UK, although it is a bit pricey to get in these days apparently.

https://en.wikipedia.org/wiki/Warwick_Castle

My parents also recommended Malvern, which is between Gloucester and Worcester. Malvern has a large priory, and is in the vicinity of the Malvern Hills

https://en.wikipedia.org/wiki/Great_Malvern_Priory

https://en.wikipedia.org/wiki/Malvern_Hills

Finally they said that Worcester is a good place to visit. Excellent cathedral, and it was also one of the most important areas during the English Civil War, if you're interested in that sort of thing.

I've been to England numerous times. In fact, we were there last spring and spent the night in Lincoln. The cathedral is incredible. Thanks for all the great advice. I think you just made my vacation a bit longer!