Scam website
This is a scam website pretending to be the online booking system of the Kilmainham Gaol Museum.
How can you know that?
1. The booking UI looks 99% the same, however the available dates and times are different.
2. Today 11am, it's still possible to purchase tickets to 9:30.
3. There is a typo in the URL: the museum is called Kilmainham Gaol, the URL is kilmaingoal. Gaol vs goal. Also Kilmainham vs kilmain seems to be suspicious.
4. No serious organization would use "lol" as a top level domain.
The original website also states that there are scam online resellers out there and even if you receive a ticket from them, it won't be valid to enter the museum.

