You cause a temple to shimmer into existence on ground you can see within range. The temple must fit within an unoccupied cube of space, up to 120' on each side. The temple remains until the spell ends. It is dedicated to whatever god, pantheon, or philosophy is represented by the holy symbol used in the casting. You make all decisions about the temples appearance. Only you and any creatures you designate when you cast the spell can open or close the door.
The temple is safe from divination, and blocks travel from the ethereal. In addition, it opposes types of creatures you choose when you cast this spell. Choose one or more of the following: celestials, elementals, fey, fiends, or undead. If a creature of the chosen type attempts to enter the temple, that creature must make a Cha saving throw. On a failed save, it can't enter the temple for 24 hours. Even if the creature can enter, the magic there hinders it; whenever it makes an attack roll, an ability check, or a saving throw inside the temple, it must roll a d4 and subtract the number rolled from their check. Casting this spell on the same spot every day for a year makes this effect permanent.
Further details are outlined in Xanathar's Guide To Everything (p167).
a holy symbol worth at least 5gp
Creo Templum Deus (then name the god)