The amphitheatre was designed as a quasi-monument to Juliusz Słowacki, who is the name patron for the estate. The local residents were supposed to meet here in order to discuss important matters as well as read the poetry of Słowacki.
The sad truth is that currently the amphitheatre is abandoned and serves as a place to meet and drink for local youth (but not only).
The cache container itself is placed outside of the theatre, in a location which is safely accessible 24/7/365. There's no need to go into the amphitheatre, especially by night (when you can meet some less fortunate folks).
In order to get to the final container, count number of stairs leading to the amphitheatre: the result should be a prime number (lower than 30) - write it down as AB.
Substitute AB to the following formula:
N 51 14. (B-A-1)(A+A)(B-A-A)
E 22 31.(A+1)(B-A-1)(B-1)
Bring your own pen.